Method for high-speed charging of secondary batteries and apparatus therefor

ABSTRACT

To provide a single universal charging apparatus, capable of charging at high speed and efficiency any type of secondary battery, and capable of charging secondary batteries any arbitrary charging rate. 
     In selecting the arbitrary amount of current from low current to high current while charging a variety of secondary batteries, the voltage and temperature of the battery are monitored, so that either at the point at which the rate of rise of the temperature of the battery exhibits an increase over the immediately previous rate of rise that exceeds a given reference value, or at the point at which the difference in change of battery voltage is decreased continuously for a preestablished amount of time, the charging of the battery is stopped.

TECHNICAL FIELD

The present invention is related to the high-speed charging of secondarybatteries and, more specifically, to a high-speed charging apparatus andhigh-speed charging method for such secondary batteries asnickel-cadmium batteries, nickel-hydrogen batteries, and lithium ionbatteries.

The present invention is configured so as to enable, with regard tonickel-cadmium, nickel-hydrogen (Ni/H2) and lithium ion secondarybatteries, the monitoring of the temperature and voltage of the batteryduring the recharging process, and so as to stop said charging processwhen these monitored parameters of either temperature or temperature andvoltage reach a particular condition.

BACKGROUND ART

Secondary batteries (secondary cells) such as Nickel-cadmium storagebatteries, nickel-hydrogen batteries, or lithium ion batteries can berecharged any number of times during their useful lifetimes. It iswidely known by persons skilled in the art that this recharging processmust be performed under careful control to minimize the damaging affectsto the storage battery. (For example refer to "Charging StorageBatteries: Extending Useful Life", Bob Williams, "Cellular Business"April, 1989, pp 44 to 49.)

At the beginning of secondary battery recharging technology, the processof recharging required as much as a number of hours. As consumerproducts powered by secondary batteries became more and more common,there arose a need for a system capable of charging times measured inminutes rather than hours.

While it is possible to fast charge a secondary battery, to preventirreversible damage to the storage battery, the storage batteryrecharging process must be performed with even more care. (For examplerefer to "Latest Information on Nickel-Cadmium Batteries" in the reportof the September 1990 Cadmium Society Brussels Seminar, published inNovember, 1990.)

Prior art has shown that a variety of systems have been developed forthe fast recharging of secondary batteries. In these systems it has beenstandard to monitor the voltage and/or temperature of the storagebattery being charged, and to interrupt or change the charging currentapplied to the storage battery when the temperature or voltage reaches apreestablished level. Typical prior art is described in U.S. Pat. No.4,006,397 (Catotti et al).

Japanese patent publications Sho 62-23528 and Sho 62-23529 disclose amethod for use in recharging of secondary batteries such asnickel-cadmium batteries, wherein the voltage waveform of the battery isobserved during charging, a number of deflection points appearing in thevoltage waveform being stored beforehand, and if the stored deflectionpoints occurred in a given sequence, the charging process isinterrupted. In this method, however, it is required for each type ofbattery to store beforehand the variations occurring in the voltagewaveform of that type of battery during the charging process, and tochange the stored contents before charging to contents appropriate tothe type of battery to be recharged, not only making operation complex,but giving no assurance, by reasons of the charging environment andhistory of the battery, that the voltage output waveform of the batterywould follow in sequence an a amplitude the stored information, therebymaking it impossible to perform accurate charging and recharging, makingit difficult to perform high-speed charging without causing loss ofbattery performance.

In addition to nickel-cadmium, nickel-hydrogen and lithium ion batteriesexist as secondary batteries.

Previously the recharging of the above-mentioned secondary batteries, itrequired from 6 hours to even as much as 16 hours in some instances, andeven with what was called fast charging at over a relatively short time,still required 1 to 2 hours.

In the past, although in recharging what were called rechargeablebatteries or storage batteries for use in their intended purposes, itwas known that it was desirable to make the charging time as short aspossible, the limitations imposed by the rise in internal batterytemperature and internal pressure in the battery caused by a chemicalreaction within the secondary battery not only lead to destruction ofthe cells, but also to a deterioration of the electrical characteristicsof the cells, that is, the output characteristics and chargingcharacteristics, so that the method of charging by means of a largecurrent over a short period of time was not used.

However, today the demand for secondary batteries is increasing in alarge of number of applications in various industries, and inparticular, there is a strong demand for secondary batteries for use inapplications such as in environments in which machine tools are used, inmedical and other equipment for hospitals, and in communications, suchas in mobile telephones, applications which not only require thatbatteries do not run down during operation but also require fast or eveninstantaneous recharging.

If a graphical comparison is made of the above-mentioned voltage andtemperature variations with respect to charge level during the chargingof the various types of secondary batteries mentioned above, it can beseen that each type of battery exhibits unique characteristics, as shownin FIG. 2 to FIG. 4.

That is, the voltage and temperature characteristics of a nickel-cadmiumstorage battery are as shown in FIG. 2, the voltage and temperaturecharacteristics of a nickel-hydrogen battery are as shown in FIG. 3, andthe voltage and temperature characteristics of a lithium ion battery areas shown in FIG. 4.

For this reason, in the past, not only did the charging Of any type ofsecondary battery require a long period of time of at least one hour,but also it had the problem of requiring a change of the charging methodor charging apparatus to suit the type of secondary battery, making theonly charging methods available troublesome, time-consuming, and costly.

The purpose of the present invention is to improve the above-describedshortcomings of the prior art, and to facilitate the recharging ofsecondary batteries, and in particular nickel-cadmium, nickel-hydrogen,and lithium ion secondary batteries, within an extremely short period oftime of from several minutes to 20 minutes. Recharging at this extremelyfast speed increases the significance of a number of parameters whichwere not so significant in the relatively slow-speed prior artrecharging systems. However, it was discovered that these parameterscould be processed so as to produce a recharging system which performssafe, high-speed charging without damaging side-effects to the storagebattery being charged.

In the past, to charge secondary batteries which consist of mutuallydiffering technical elements, and which have differing chargingcharacteristics and behavior, it was necessary to make availableseparate chargers and to select the charger appropriate for charging thetype of secondary battery to be charged.

Therefore, the charger was something to be used only for the charging ofa particular type of secondary battery, it being necessary to makeavailable individual chargers for individual secondary batteries, makingthe charging operation not only inconvenient, but troublesome andcomplex as well.

Even for the same type of secondary batteries, if an amount of chargingcurrent used in a charging operation, which is generally represented bya charge rate C, differ, the chargers would have to be providedseparately, causing the problem of the heed to have a considerablenumber of charger types available.

However, with the demand for such secondary batteries increasing, andwith a diversification in the fields and location in which secondarybatteries are used, there has arisen an increasing need for a chargercapable of use anywhere in charging any type of secondary batterycompletely within a short period of time, for applications requiringquick charging and immediate use of secondary batteries, such as inmobile data communications, mobile telephone communications, and atconstruction sites.

For this reason, the is a desire to have a single charger not onlycapable of charging a secondary battery of any type of construction, butalso capable of charging under any charging rate C conditions. However,until the present, there has been no such practically usable charger.

Therefore, the object of the present invention is to improve on thedefects described above, and provide a single charger which isuniversally usable to charge any type of secondary battery in a shortperiod of time under any arbitrary charging rate C.

DISCLOSURE OF INVENTION

To solve the above-described problems, the present invention has thefollowing technical configuration. Specifically, the first aspect of themethod of high-speed charging of secondary batteries of the presentinvention is a method for charging secondary batteries comprising, astep 1 which sets the basic data reading time tb required to read data,a step 2 which sets the charging rate C, a step 3 which sets thecorrected data reading time tc, according to the set charging rate C andsaid basic data reading time tb, said corrected data reading time tcbeing characteristic to said charging rate C, a step 4 which, during thecharging operation, uses an appropriate sampling means to measure theterminal voltage of said secondary battery at least one time during eachsaid corrected data reading time tc, and which stores the voltage dataat that time into an appropriate 1st memory means, a step 5 whichrepeats the operation of said step 4 a predetermined number of times L,takes the summation of the plurality of voltage data obtained in eachcorrected data reading time tc, and stores the resulting amount ofchange Dvn over the amount of voltage data change reading sampling timets (where ts=L×tc) into an appropriate 2nd memory means, a step 6 whichcalculates the difference between the amount of change Dv1 for the 1stsampling time (ts1) and the amount of change Dv2 for the next, 2nd,sampling time (ts2) obtained in step 5, and which stores the resultingdifference in amount of change ΔDv in a 3rd memory means, a step 7 whichcontinuously repeats said step 6 a predetermined number of times M, andwhich takes the summation of each of the values of ΔDv1 to ΔDvM (Mvalues) obtained at each amount of change reading sampling time (ts),and determines the amount of voltage data change ΔTDv for the overallsaid amount of change reading sampling time t (where t=ts×M), theresults being stored in a 4th memory means, a step 8 which performs acalculation, based on the amount of voltage data change ΔTDv stored insaid 4th memory means, to determine the difference ΔHv between thevoltage amount of change ΔTDv1 measured from over the first overallamount of change reading sampling time t1 established as running fromsaid 1st sampling time (ts1) to the mth sampling time (tsM) for thepredetermined M-th sampling, and the voltage amount of change ΔTDv2measured from over the second overall amount of change reading samplingtime established as running from said 2nd sampling time (ts2) to the(m+1)th sampling time (tsM+1) for the predetermined M+1-th sampling,said calculated difference ΔHv (where ΔHv=ΔTDv2-ΔTDv1) being stored in a5th memory means, a step 9 which repeats said step 8 while calculatingthe difference value ΔHvn (where ΔHvn=ΔTDv(N+1)-ΔTDvn) between theamount of voltage changes ΔTDvn and ΔTDv(n+1) at each pair of adjacentoverall amount of change sampling times tn and tn+1, and stores thecalculated results in 5th memory means, a step 10 which judges whethereach of the m amounts of differences in amount of voltage changes ΔHv1to ΔHvm obtained continuously in said step 9 are positive (zero orgreater than zero) or negative (less than zero), and a step 11 whichjudges, in the sequence of occurrence of said differences in amount ofvoltage changes ΔHv1 to ΔHvm, whether or not said difference in amountof voltage change ΔHv is zero or negative for a predetermined number ofS times continuously, and if said difference in amount of voltage changeΔHv is zero or negative S times continuously, stops said charging.

Additionally, the second aspect of the method of high-speed charging ofsecondary batteries of the present invention is a method for chargingsecondary batteries comprising, a step 1 which sets the basic datareading time tb required to read data, a step 2 which sets the chargingrate C, a step 3 which sets the corrected data reading time tc,according to the set charging rate C and said basic data reading timetb, said corrected data reading time tc being characteristic to saidcharging rate C, a step 4 which, during the charging operation, uses anappropriate sampling means to measure the temperature of said secondarybattery at least one time during each said corrected data reading timetc, and which stores the temperature data at that time in an appropriate1st memory means, a step 5 which repeats the operation of said step 4 apredetermined number of times L, takes the summation of the plurality ofdata obtained in each corrected data reading time tc, and stores theresulting amount of change Dtn over the amount of temperature datachange reading sampling time ts (where ts=L×tc) into an appropriate 2ndmemory means, a step 6 which calculates the difference between theamount of change Dt1 for the 1st sampling time (ts1) and the amount ofchange Dt2 for the next, 2nd, sampling time (ts2) obtained in step 5,and which stores the resulting difference in amount of change ΔDt in a3rd memory means, a step 7 which continuously repeats said step 6 apredetermined number of times M, and which takes the summation of eachof the values of ΔDt1 to ΔDtM (M values) obtained at each amount ofchange reading sampling time (ts), and determines the amount oftemperature data change ΔTDt for the overall said amount of temperaturechange reading sampling time t (where t=ts×M), the results being storedin a 4th memory means, a step 8 which performs a calculation, based onthe values of amount of temperature data change ΔTDt stored in said 4thmemory means, to determine the ratio between the temperature amount ofchange ΔTDt1 measured from over a first overall amount of change readingsampling time t1 established as running from said 1st sampling time(ts1) to the sampling time (tsM) for the predetermined M-th sampling,and the temperature amount of change ΔTDt2 measured from over a secondoverall amount of change reading sampling time t2 established as runningfrom said 2nd sampling time (ts2) to the sampling time (tsM+1) for thepredetermined M+1-th sampling, said calculated ratio ΔHt (whereΔHt=ΔTDt2/ΔTDt1) being stored in a 5th memory means, a step 9 whichrepeats the operations of said step 8 while calculating the ratio valueΔHtn (where ΔHtn=ΔTDt(N+1)/ΔTDtn) between the amount of temperaturechanges ΔTDtn and ΔTDt(n+1) at each pair of adjacent overall amount ofchange sampling times tn and tn+1, and stores the calculated results in5th memory means, a step 10 which judges from the information stored insaid 5th memory means whether the ratio ΔHm between two adjacent saidtemperature amounts of change is equal to or greater than or is lessthan a given value K, and a step 11 which, if the temperature amount ofchange ratio ΔHm value is equal to or greater than the given value K,stops said charging.

In addition, it is possible to think of the coupling of the twoabove-described aspects of the present invention of a high-speedsecondary battery charging method as a third aspect of the presentinvention.

Because the high-speed charging method for secondary batteries of thepresent invention makes use of the above-described basic technicalconfiguration, even for secondary batteries of differing types, inconsideration of the mutually differing charging characteristicsexhibited by the secondary batteries, such as terminal voltage ortemperature, it is possible to determine the common characteristics ofsecondary batteries having differing constituent elements, to accuratedetermine point at which the charge level reaches nearly 100%, enablingnot only one and the same apparatus to be used to reliably chargesecondary batteries of differing construction, but also enabling theaccurate determination of the charge level during the charging process,the quick determination of the point at which the charge level reaches alevel of nearly 100%, and the stopping of the charging process at thatpoint, the result being not only a reliable avoidance of the problemencountered when the charging is continued even after the charge levelhas exceeded 100%, thereby causing the temperature of the secondarybattery to rise above its rated maximum temperature, leading to damageto said secondary battery, but also a determination of thecharacteristics of said secondary battery with respect to the speed ofcharge, or charge rate, thereby enabling charging of secondary batterieswhich are of the same constituent elements at different charge rates,further enabling in particular the precise high-speed charging ofsecondary batteries.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram which shows the configuration of a specificexample of the high-speed charging apparatus for secondary batteries ofthe present invention.

FIG. 2 is a graph which shows the charging characteristics of anickel-cadmium battery.

FIG. 3 is a graph which shows the charging characteristics of anickel-hydrogen battery.

FIG. 4 is a graph which shows the charging characteristics of a lithiumion battery.

FIG. 5 (A) is a drawing which shows a curve of measurement data and therelationship of the sampling interval p to the amount of change, andFIG. 5 (B) is a drawing which shows the relationship of the measurementdata sampling period t and the measurement data amount of change readingsampling time (ts) for the present invention.

FIG. 6 (A) is a drawing which describes one example of analysis of thevoltage measurement data and condition of change thereof in the presentinvention, and FIG. 6 (B) is a drawing which describes one example ofanalysis of the temperature measurement data and condition of changethereof in the present invention

FIG. 7 is a flowchart which shows one example of the procedure in thecase of executing the secondary battery charging method of the presentinvention.

FIG. 8 is a flowchart which shows one example of the procedure in thecase of executing the secondary battery charging method of the presentinvention.

FIG. 9 is a flowchart which shows one example of the procedure in thecase of executing the secondary battery charging method of the presentinvention.

FIG. 10 is a flowchart which shows another example of the procedure inthe case of executing the secondary battery charging method of thepresent invention.

FIG. 11 is a flowchart which shows one example of the procedure in thecase of executing the secondary battery charging method of the presentinvention.

FIG. 12 is a graph showing one example of the voltage characteristics ofa nickel-cadmium battery when charged at 0.25 C.

FIG. 13 is a graph showing the a graph of the changes in the overallvoltage amount of change ΔTDvn and the counter value N when the chargingof FIG. 12 is done.

FIG. 14 is a graph showing one example of the temperaturecharacteristics of a nickel-cadmium battery when charged at 3 C.

FIG. 15 is a graph showing one example of the voltage characteristics ofa nickel-cadmium battery when charged at 3 C.

FIG. 16 is a graph showing the a graph of the changes in the overallvoltage amount of change ΔTDvn and the counter value N when the chargingof FIG. 15 is done.

FIG. 17 is a graph showing one example of the voltage characteristics ofa nickel-hydrogen battery when charged at 0.25 C.

FIG. 18 is a graph showing the a graph of the changes in the overallvoltage amount of change ΔTDvn and the counter value N when the chargingof FIG. 17 is done.

FIG. 19 is a graph showing one example of the voltage characteristics ofa nickel-hydrogen battery when charged at 1 C.

FIG. 20 is a graph showing the a graph of the changes in the overallvoltage amount of change ΔTDvn and the counter value N when the chargingof FIG. 19 is done.

BEST MODE FOR CARRYING OUT THE INVENTION

The following is a detailed description, presented with reference todrawings, of concrete examples of the method and apparatus high-speedcharging of secondary batteries of the present invention.

The background of why the inventors of the present invention employedthe above-described technical configuration in the method for high-speedcharging of secondary batteries of the present invention starts with theinventors of the present invention making a thorough analysis andinvestigation of the charging characteristics of secondary batteriesthat have been commercially available in the past, and making efforts todetermine, for the purposes of fulfilling the above-described object ofthe present invention, the desired form of a single apparatus and methodfor performing high-speed charging of different types of secondarybatteries, for performing precise charging even if the charging rate isvaried with respect to said secondary batteries of differing types, andfurther for performing high-speed charging of said secondary batteriesof differing types.

The inventors, then, analyzed, the nickel-cadmium batteries,nickel-hydrogen batteries, and lithium ion batteries, which were thoughtto be the important types of those types commercially available in thepast, the result of this analysis being that in general fornickel-cadmium batteries, as shown in FIG. 2, the terminal voltageduring charging continues a gradual increase up to the point at which100% charge level is reached, at which point a peak voltage is reached,with further charging causing a decrease in voltage.

When the temperature of a nickel-cadmium battery is observed, there is aslight increase in temperature from the start of charging to just beforethe 100% charge level, and although the overall characteristics isvirtually flat with no extremely temperature increase, except when the100% charge level region is approached, when there is a sudden increasein temperature.

In the case of nickel-hydrogen batteries, which is shown in FIG. 3, thebattery terminal voltage continues its gradual increase from the startof the charge until the 100% charge level, and when the charge levelreaches 100% the voltage value exhibits the peak value, after whichsubsequent charging results in no further change the battery voltage,which maintains the peak value.

The temperature of a nickel-hydrogen battery, similar to anickel-cadmium battery, gradually increase from the start of charging tojust before the 100% charge level, and although the overallcharacteristics is virtually flat with no extremely temperatureincrease, except when the 100% charge level region is approached, whenthere is a sudden increase in temperature.

In the case of yet another type of secondary batteries, lithium ionbatteries, as shown in FIG. 4, the battery terminal voltage increasingapproximately in direct proportion to elapsed time, from the start ofcharging to the 100% charge level, and when the 100% charge level isreached, the voltage value exhibits the peak value, after whichsubsequent charging results in no further change in the battery voltage,which maintains the peak value.

The battery temperature in the case of a lithium ion secondary batteryexhibits a gradual increase from the start of charging, which, duringthe charging process, changes to a gradual increase, until the 100%charge level is reached, at which point the battery temperatureincreases sharply as the same configuration as that of thenickel-cadmium battery.

In an ideal secondary battery, the energy of the current caused to flowin the battery until the 100% charge level is reached is spent in thechemical reaction required for charging, and is not converted to thermalenergy.

However, after approaching the 100% charge level, the rate of saidchemical reaction becomes slow, the remaining energy being spent in achemical reaction not related to charging, and converted to thermalenergy.

Therefore, after the charge level reaches 100%, the reactioncontributing to charging does not occur immediately, gas is formed, andthe temperature rises.

When the temperature rises, the speed of the chemical reactionincreases, causing the temperature to rise, and this also causes a greatdeal of gas to be generated.

These phenomena form a vicious circle, and ultimately lead to thedestruction of the battery.

If the charging operation is performed repeatedly, the matter inside thebattery which contributes to the occurrence of the chemical reactiondeteriorates, so that it is not possible to store sufficient energy.

Therefore, as described above, if charging is continued even after thecharge level reaches 100%, a problem arises in that the deterioration ofinternal matter in the battery is accelerated, resulting in a lifetimefor the battery considerable shorter than the intended life of thesecondary battery.

For that reason, in the past, because of limitation imposed because ofthe makeup and characteristics of secondary batteries, said chargingoperation was only possible by means of very limited methods, and it wasnot possible to solve the problems cited above.

Charging methods in the past have included, for example, the following.

(1) Charging with a minute (trickle) current (for example, a current of1/10 to 1/20 of the capacity of the battery), and performing no controlat the point at which charging is completed.

In this charging method, there is absolutely not control of the current,and the charging time generally ends in approximately 10 hours to 15hours.

For this reason, in this charging method, the charging time becomesextremely long, and there is a danger or overcharging.

(2) Charging with a small current (for example, a current of 1/3 to 1/10of the capacity of the battery), with the end of controlled as beingafter a preestablished time, which was generally 5 hours to 10 hours.

In this charging method, the charging time becomes long, and there is adanger of temperature rise caused by excessive current in the case inwhich the battery had some remaining capacity.

(3) Charging with a relatively large current (for example, a current of1/3 to 1/1 of the battery capacity), and stopping the charging when thevoltage value of the battery being charged falls below a given value(generally approximately 10 mV per cell).

The time for completion of the charging is approximately 1 hour, andthis is what is known as relatively fast charging.

In this charging method, while the charging time is relatively short,there is a great danger of excessive current, and a large rise intemperature.

Additionally, in this method, it is impossible to detect the completionof charging in batteries having characteristics such as were describedin FIG. 2 and FIG. 3.

For this reason, in the present invention, in consideration of thecharacteristics of a variety of previous secondary battery types,characteristics heretofore unknown, which are common to secondarybatteries are employed in achieving the above-stated object of thepresent invention.

Specifically, in the high-speed charging method for secondary batteriesof the present invention, a method and an apparatus for high-speedcharging of secondary batteries is provided which makes possible thereliable stopping of charging of any type of secondary battery at apoint in the charge level of 95% to 100%, charging at current levelsranging from small to large (for example, equal to or greater than thecapacity of the battery), and in particular, high-speed charging, forexample at a charge rate of 2 C in an extremely short period of time,for example 15 minutes or less.

What follows is a description of the high-speed charging method andapparatus of the present invention, with reference made to drawings.

FIG. 1 shows a block diagram of one concrete example of theconfiguration of the high-speed charging apparatus for secondarybatteries of the present invention, which basically shows an apparatusfor high-speed charging of secondary batteries 1, comprising, acurrent-supplying means 3 which supplies electrical current to the cellsof a secondary battery 2 requiring charging, a switch means 5 providedbetween said current-supplying means 3 and terminal 4 of said secondarybattery being charged, a temperature measurement means 6 which measuresthe temperature of said cells of said secondary battery 2, a voltagemeasurement means 7 which measures the terminal voltage of saidsecondary battery, a sampling means 8 which operates saidtemperature-measurement means 6 and/or said voltage measurement means 7to measure the temperature and/or the voltage of said cells of saidsecondary battery 2 with the desired sampling interval, a storage device30 which stores each of the data sampled by said sampling means 8, andwhich executes the required calculations on said stored data, storingthe results in a separate memory means, a charging-control means 9 whichis connected to said sampling means and controls said switch means 5, acharging rate setting means 10 which sets the charging rate C, a basicdata reading timing generator means 11 which, based on the charging rateC set by said charging rate setting means 10, generates thepredetermined basic data reading time tb, a corrected data reading timesetting means 12 which, set the corrected data reading time tc, thevalue of which is characteristic to said charging rate C, an amount ofdata change reading sampling time setting means 13 which multiplies thecorrected data reading time tc by a preestablished value L to set thetemperature data amount of change reading sampling time ts, an overallsampling time setting means 14 which multiplies said data amount ofchange reading sampling time ts by a preestablished value M to set theoverall sampling time t, a 1st memory means 15 which stores the valuesof temperature data dtn measured each said corrected data reading timetc, a 2nd memory means 16 which stores the data Dtn which is thesummation of the L values of temperature data dtn stored in said 1stmemory means 15, a 3rd memory means 17 which, from the data Dtn storedin said 2nd memory means, stores the difference ΔDt between data Dt(n-1)measured at the previous amount of change reading sampling time ts anddata Dtn measured at the current amount of change reading sampling timets+1, this difference value being ΔDt (where ΔDt=Dtn-Dt(n-1)), a 4thmemory means 18 which stores the amount of temperature data change ΔTDtobtained by taking the summation of each of the M amounts of temperaturedata obtained at each amount of change reading sampling time (ts) in theoverall amount of change reading sampling time t (where t=ts×M) obtainedby repeating said amount of change reading sampling time (ts) M therequired number of M times, a 5th memory means 19(A) which, with regardto the temperature data amount of change ΔTDt stored in said 4th memorymeans 18, stores the change ratio ΔHt calculated between the amount oftemperature data change ΔTDtn at the 1st overall amount of changereading sampling time tn and the amount of temperature data changeΔTDt(n+1) at the 2nd overall amount of change reading sampling timetn+1, which is formed by shifting the time by one amount of changereading sampling time (ts), said change ratio being ΔHt (whereΔHt=ΔTDt(n+1)/ΔTDtn), a 1st judgment means 22 which compares saidtemperature change ratio ΔHt which are stored in said 5th memory means19(A) between said amounts of temperature change with a preestablishedreference value K, and if said change ratio ΔHtm between said amounts oftemperature change exceeds said reference value K, outputs a signalwhich stops said charging, a 6th memory means 19(B) which, with regardto the terminal voltage data amount of change ΔTDv stored in said 4thmemory means, stores the difference calculated between the amount oftemperature data change ΔTDvn at the 1st overall amount of changereading sampling time tn and the amount of temperature data changeΔTDv(n+1) at the 2nd overall amount of change reading sampling timetn+1, which is formed by shifting the time by one amount of changereading sampling time (ts), said difference being ΔHvm (whereΔHvm=Hv(m+1)-Hvm), a 2nd judgment means 23 which, with regard to eachthe m values of voltage data amounts of change differences ΔHv1 to ΔHvmstored continuously in said 6th memory means 19(B), makes a judgment asto whether the values are positive (zero or larger) or negative (lessthan zero), and which performs said judgment processing in the sequenceof occurrence of said voltage data amount of change differences ΔHv1 toΔHvm, and if said voltage data amount of change difference ΔHv is anegative value a preestablished number of times S or more continuously,output s signal which stops said charging operation, and a processingmeans 24 which processes each of the individual data stored by each ofsaid means, and a central processing means 25 which controls theoperation of each said means.

In the present invention, one and the same high-speed secondary batterycharging apparatus is capable of performing high-speed charging of, asdescribed above, nickel-cadmium batteries, a nickel-hydrogen batteries,or a lithium ion batteries.

One of the characteristics of the present invention is that, for thepurpose of performing precise, high-speed charging of any secondarybattery, a comprehensive study of the characteristics of said secondarybatteries was made, and the configuration was made so as to enableaccurate and quick detection of changes in characteristics values ofsaid secondary batteries, enabling not only reliable detection of thepoint at which said secondary batteries reach a condition in which theyare as close as can be to the 100% charge level, but also stopping ofthe charging process at that point, and to enable this performance, thepresent invention is configured to perform measurement of voltage dataand/or voltage data of said secondary batteries at an extremely shortinterval, the results of these measurements being used to effectivelydetermine the charging condition of said secondary batteries.

More specifically, in the charging operation performed by the presentinvention, in order to make a judgment of whether or not the chargelevel of 100% or the 100% region has been reached, regardless of whichtype of secondary battery is being charged, as shown in FIG. 2 throughFIG. 4, it is appropriate to detect the point of the occurrence of apeak value in the voltage data, or, in the temperature data, to detectthe point at which the temperature rises at a sudden high rate.

For example, in measuring voltage data, as shown in FIG. 5 (A), withprevious methods, to make the amount of data change Δa large, it isnecessary to make the sampling interval p a somewhat long interval.

However, in charging, if the sampling interval p is long, as shown inFIG. 5 (A), there is the problem of losing the opportunity of detectingthe peak in the voltage data, thus making it impossible to detect theproper time to stop charging.

On the other hand, if the sampling interval p is made short, the cost ofreading the amounts of data change Δa becomes very high, making itimpossible to implement an economic system.

For this reason, in the present invention, the basic data reading timetb required to read data is set, a corrected data reading time tc, whichis characteristic to the charging rate C is set based on that time andthe charging rate, the terminal voltage of said battery and/or surfacetemperature of said battery is measured one time each within saidcorrected data reading time tc, these operations being repeated apreestablished number of times L, the voltage data and/or temperaturedata from which operations are summed separately, the summed data beingtaken as the variable Dn with respect to the amount of data changereading sampling time ts (where ts=L×tc). Refer to the graph of FIG. 5(B).

By virtue of these operations, the apparent accuracy of the measuredvoltage data and/or temperature data is thus multiplied by L.

A 3rd memory means 17 which, from the data Dtn stored in said 2nd memorymeans, stores the difference between data Dt(n-1) measured at theprevious amount of change reading sampling time ts and data Dtn measuredat the current amount of change reading sampling time ts+1, thisdifference value being ΔD (where ΔD=Dtn-D(n-1));

Next, in the present invention, the difference between the variable Dnat said amount of data change reading sampling time ts (where ts=L×tc)and the variable D(n-1) at said previous amount of data change readingsampling time ts is determined as ΔD (where ΔD=Dtn-D(n-1)), the resultsbeing sequentially stored in 3rd memory means 17.

Subsequently, these operations are repeated a preestablished number oftimes M, the total, as shown in FIG. 5 (B), being taken as the amount ofvoltage data and/or temperature data change ΔTD for the overall saidamount of change reading sampling time t (where t=ts×M).

After that, as shown in FIG. 5 (B), the overall said amount of changereading sampling time t and said data amount of change reading samplingtime ts are each shifted by one at a time, as the amount of temperaturedata and/or voltage data change ΔTD1 to ΔTDm for respective overallamount of change reading sampling times t1 to tm is determined.

Therefore, ultimately in the present invention, the time of measuringthe voltage data and/or temperature data amount of change ΔTD isexpressed as t=M×L×tb×A/C.

Therefore, in the present invention, by properly selecting the values ofthe above-stated constants M and L, it is possible, with a low-costreading apparatus, not only to read measurement data with high accuracy,but also, because the range obtained by shifting said overall amount ofchange reading sampling time (ts) is shifted one at a time is set, sothat said voltage data and/or temperature data amount of change ΔTD isobtained at an interval which is said amount of change reading samplingtime (ts), it is possible to obtain the large amount of change data ΔTDwhich is sampled at the relatively long interval of the overall amountof change reading sampling time t, within the relative short time whichis the amount of data change sampling time (ts), it is possible todetermine at a short sampling interval whether or not to stop charging,resulting in a detailed and precise charging operation.

In addition, in the present-invention, for the purpose of performinghigh-speed charging, and in consideration of the fact that saidsecondary batteries of differing types are used, the measurementconditions are changed, the configuration is made such that, accordingto the the speed of charging, or what is normally called the chargingrate, so that high or low charging speeds can be employed to obtain theoptimum charging operation.

The apparatus for high-speed charging of secondary batteries 1 of thepresent invention, is provided with a switch means 5 which is connectedbetween the terminal 4 of the secondary battery being charged and thecurrent-supplying means 3 for the purpose of supplying charging currentto a secondary battery 2 requiring charging, said switch means 5 beingcontrolled by said charging-control means 9, so that the current fromsaid current-supplying means 3 is on and off controlled.

In performing charging of said secondary battery 2, said switch means 5is turned on, so that current flows from said current-supplying means 3to said secondary battery 2 of said secondary battery, and when thecharge level of said secondary battery reaches 100% or when, asdescribed later, a condition is detected which indicates that saidsecondary battery is approaching the 100% charge level, said switchmeans 5 is switched off, and the current from said current-supplyingmeans 3 to said secondary battery 2 is cut off.

In the present invention, as described later, when measuring voltageand/or temperature at each sampling time, it is desirable to make themeasurement with said charging current cut off, and in this case, whenmeasuring the above-stated data, intermittent drive is used, so thatsaid switch means 5 is cut off in synchronization with the samplingsignal of said sampling times.

In addition, from the measurement results of each of said data, when ameasured data is detected which is outside the range of normally allowedvalues, it is also possible to turn said switch means 5 off, so that thecharging operation is stopped.

The reason for this is that, in the present invention, in measuring theabove-stated voltage and/or temperature, if a measurement is made withthe charging current flowing from said current-supplying means 3 to saidsecondary battery 2, because there will not be a uniform reactionoccurring within the battery, the voltage value will include an error,making the acquisition of accurate measurement data impossible.

As described above, when a measurement is performed while chargingcurrent is flowing, it is impossible to avoid contact resistance betweensaid secondary battery and the charging apparatus, so that, for example,a voltage drop will develop across the contact resistance due to thecharging current, this also making it difficult to obtain accuratemeasurement data.

Next, in the present invention, a microcomputer is used to measure alarge amount of terminal voltage and battery surface temperature voltagefor the secondary battery in an extremely short period of time, and toanalyze the results of these measurements, making judgments as towhether or not the secondary battery has reached a charge level of 100%or the region near 100% as it tracks the minute variations of secondarybattery characteristic values.

Furthermore, in the present invention, the configuration is such thateven if the charging rate C, which is a charging condition, is varied,it is possible to complete precise charging in a short period of time.

For this reason, in the apparatus for high-speed charging of secondarybatteries 1 of the present invention, there is provided a charging ratesetting means 10, for the purpose of adjusting the speed of charging,that is the charging rate C, to the characteristics charging rate of thesecondary battery to be charged.

By virtue of the above, it is possible to set the sampling period formeasurement during the charging operation to a value that is optimizedwith respect to the charging rate C for said secondary battery.

In the apparatus for high-speed charging of secondary batteries 1 of thepresent invention, there is provided as part of the circuitconfiguration a basic data reading timing generator means 11 which setsthe basic data reading time tb, the basic data reading time tb generatedby said basic data reading timing generator means 11 being adjusted bycorrected data reading time setting means 12, based on the charging rateC set by said charging rate setting means 10, so that the corrected datareading time tc is characteristic to the charge rate C of said secondarybattery.

In this case, the corrected data reading time tc, data change ΔTD atsaid overall amount of change reading sampling time t (t=tx×M) beingdetermined, and result for voltage data and temperature data beingstored separately in 4th memory means 18.

Because subsequent operation differs slightly between voltage data andtemperature data, the operation for voltage data will be describedfirst.

First, using the amount of voltage data change ΔTDv which was stored insaid 4th memory means 18, the difference between the voltage amount ofchange ΔTDv1 measured from over the said overall amount of changereading sampling time established as running from said 1st sampling time(ts1) to the sampling time (tsM) for the M-th sampling, and the voltageamount of change ΔTDv2 measured from over the overall amount of changereading sampling time established as running from said 2nd sampling time(ts2) to the sampling time (tsM+1) for the M+1-th sampling is determinedby calculation, said calculated difference ΔHv being stored in a 5thmemory means.

These operations are performed continuously, and a general descriptionof the above operations is that, with respect to the measured amount ofvoltage change ΔTDvn at a given overall amount of voltage data changereading sampling time tn, said amount of change reading sampling time(ts) is shifted one at a time, while continuous repeated calculation isperformed of the amount of voltage changes ΔTDvn to ΔTDv(n+x) at saidoverall amount of change sampling reading times t(n+1) to t(n+x), whichare derived constantly by summing M of said amount of change readingsampling times (ts), and, similar to as described previously, these arestored in said 4th memory means 18, while the amount of voltage changesΔTDvn and ΔTDv(n+1) occurring at adjacent overall amount of changereading sampling times tn and t(n+1) are used to calculate thedifference value ΔHvn (where ΔHvn=ΔTDv(n+1)-ΔTDvn), this being stored in6th memory means 19(B).

With respect to the m continuously obtained values of amount of voltagechange differences ΔHv1 to ΔHvm, a judgment is made by 2nd judgmentmeans 23 as to whether a value is positive (zero or greater) or negative(less than zero), and said 2nd judgment means 23 further executes ajudgment processing in the sequence of occurrence of said amount ofvoltage change differences ΔHv1 to ΔHvm, to make a judgment as towhether or not at least a preestablished number of continuous values ofsaid amount of voltage change difference ΔHv is or is not negative, andif S continuous values of said amount of voltage change difference ΔHvare negative, a judgment is made that said secondary battery has reachedthe 100% charge level or is in the 100% charge level region, and asignal is output for the purpose of stopping said charging operation,which causes said charging-control means 9 to operate to turn switchmeans 5 off, and stop the charging operation with respect to saidsecondary battery.

Essentially, as shown in FIG. 6A, when an approach is made to the fullycharged condition, the rising curve of said voltage data becomesgradual, and the above-mentioned difference becomes either zero ornegative.

Then, in the case in which said difference value is either zero ornegative, an appropriate counter value is advanced by 1, and when saidcounter value reaches a given value of, for example, 3, said chargingoperation is stopped.

What this means is that with the method of stopping the charging asdescribed above in the present invention, if the difference between theprevious value of voltage of the secondary battery and the current valueof voltage of the secondary battery is either zero or negative for 3times in a row, it will be assumed that the secondary battery hasreached a 100% charge level, and the charging which is set in accordancewith said charging rate C and said basic data reading time tb, can alsobe expressed as tc=tb×A/C (where A is a constant).

The above constant A can be set as appropriate, for example, as apositive integer such as 16.

In the present invention, during the charging of the battery, thebattery terminal voltage or battery temperature is measured by means ofsaid sampling means 8 at least one time during said corrected readingtime tc, the voltage data or temperature data d at that point beingseparately stored in an appropriate 1st memory means 15, saidmeasurement operations being repeated continuously a preestablishednumber of times L, with the plurality of voltage data obtained at eachof the corrected reading times tc being summed, the amount of change Dnin the resulting voltage data or temperature data at the amount ofchange sampling time ts (where ts=L×tc), for example Dvn and Dtn, beingstored in an appropriate 2nd memory means 16.

Next, in the present invention the difference between the amount ofchange D1 at the 1st sampling time (ts1), which was stored in the 2ndmemory means 16 and the amount of change D2 at the next, 2nd, samplingtime (ts2), which was stored in said 2nd memory means 16 is determinedby calculation, the results being the differences in amount of changeΔD, which are stored in 3rd memory means 17.

In the present invention, during a preestablished period, which is theoverall amount of data change reading sampling time t, these operationsare repeated continuously a preestablished M number of times, with theoverall amount of data change reading sampling time t expressed ast=tx×M.

In the present invention, the measured values of data ΔD1 to ΔDMobtained by performing repeated continuous measurements during saidamount of data change reading sampling time are summed, the amount ofvoltage operation will be stopped.

In the case of measuring the surface temperature of the secondarybattery, of the temperature data amount of change values ΔTDt stored insaid 4th memory means 18, a calculation is performed to determine thechange ratio between the temperature data amount of change ΔTDtn at the1st overall amount of change reading sampling time tn and the 2ndoverall amount of change reading sampling time t(n+1), which is formedby shifting by said amount of change reading sampling time (ts) at atime, this change ratio of ΔHt (where ΔHt=ΔTDt(n+1)/ΔTDtn) being storedin 5th memory means 19(A).

Subsequently, said change ratio ΔHt between amounts of temperaturechange is compared by 1st judgment means 22 with a preestablishedreference value K, and if said change ratio ΔHt between amounts oftemperature change exceeds said reference value K, a signal is outputfrom 1st judgment means 22 for the purpose of stopping said chargingoperation.

Thus, as shown in FIG. 6B, in the region of full charge, since in therising curve of measured temperatures of the secondary battery suddenlyincreases, the ratios of ΔTDt(n+1) and ΔTDtn for each amount of changereading sampling time (ts) is taken, and if said ratio is greater than apreestablished reference value K, it is assumed that said secondarybattery has reached 100% charge level, and the charging operation isstopped.

In said 1st judgment means 22, if said change ratio ΔHt between amountsof temperature change differences exceeds a preestablished referencevalue K, the judgment will be made that said secondary battery hasreached 100% charge level or the 100% charge level region, and a signalwill be output for the purpose of stopping said charging operation, theresult being that said charging-control means 9 is operated to turn saidswitch means 5 off, thereby stopping the charging operation of saidsecondary battery.

With regard to the present invention, although the method of measuringthe terminal voltage of said secondary battery during charging andstopping the charging operation if the judgment is made that the chargelevel has reached 100% or the 100% region, and the method of measuringthe temperature of said secondary battery during charging and stoppingthe charging operation if the judgment is made that the charge level hasreached 100% or the 100% region were described separately, in thepresent invention it is possible to combine these two methods, therebyenabling a more accurate determination of the charge level.

Additionally, in the present invention, although the basic method iswhen measuring voltage data, to measure the voltage data measured ateach amount of change reading sampling time (ts), repeating this Mtimes, thereby accumulating the overall data value during the overallsampling period t (ts×M), using the results to observe the change ofsaid voltage data, in the charging of a secondary battery, when thecharge level of said secondary battery is 100% or is in the 100% region,the change in temperature becomes very gradual, so that if the samplingperiod is made long, it is possible to, for example, detect the peakvalue on the temperature variation graph, or to accurately and quicklydetect such conditions as a dropoff from the peak value, or in addition,the condition in which there is no change from the peak value over agiven period of time.

For this reason, in the high-speed charging method for secondarybatteries of the present invention, another possible form is that inwhich, every time a voltage data amount of change ΔTDvn is measured eachsaid amount of change reading sampling time (ts), a difference betweenthat value and the previously determined voltage data amount of changeΔTDv(n-1) is determined, a determination is made as to whether thatvalue is either zero or positive or zero, and if the value is positive,a counter ΔS having a preestablished upper limit value W is reset tozero, but if the value is negative, the current said counter value ΔS isincremented by 1, or a value corresponding to said negative value isadded to the ΔS, and if the resulting sum exceeds the preestablishedupper limit value W, the charging operation with regard to saidsecondary battery is stopped.

In the case in which said difference amount is zero, it is possible, forexample, to forcibly add a preestablished negative constant Z (forexample -2) to said counter value ΔS, so that if the difference value iszero, indicating that the voltage data curve is not changing, it istreated as if it were a negative value for the purposes of processing.

Next, one concrete example of the operating procedure for the high-speedcharging method for secondary battery of the present invention will bedescribed, with references made to the flowcharts of FIG. 7 through FIG.9.

FIG. 7 through FIG. 9 are flowcharts that explain the operation of onespecific example of the high-speed charging method for secondarybatteries of the present invention. First, at step (1), the basic datareading time tb required to read data is set, operation proceeding tostep (2), at which the charging rate C which is a rated value suitablefor executing charging with respect to said secondary battery.

In the present invention, in addition to being able to charge secondarybatteries having individually differing constructions, there beingsecondary batteries of the same type but having differing chargingrates, it is possible to also, in accordance with the charging rate thatis indicated as a specification, by executing sampling of the idealmeasurement values, to collect precise data, enabling accurate andhigh-speed charging.

Next, operation proceeds to step (3), at which the corrected datareading time tc, which is characteristic to the set charging rate C isset in accordance with the set charging rate C and said basic datareading time tb.

Then, at step (4), since in the case in which the measured voltage valueamount of change is either zero or negative a preestablished number oftimes, for example P, in a row, the judgment is made that said secondarybattery being charged has reached the 100% charge level or the region of100% charge level, and said charging operation is stopped, if thisoccurs, at this step the preestablished value of P is set into thecounter I, which counts down.

At step (5), in order to repeat the sampling operation every correcteddata reading time tc, which value is characteristics to the chargingrate C, for example L times, said preestablished number of times L isset into counter II, which controls said number of repetitions.

Next, operation proceeds to step (6), at which the time datacorresponding to the corrected data reading time, which ischaracteristics to-the charging rate and which is set at step (3), isset into counter III.

After this, at step (7), when measuring the voltage and temperature dataof the secondary battery being charged, for the reason describedpreviously, the supply of current to charging said secondary battery iscut off at the instant of the data measurement.

As described previously, the charging current at the time of these datameasurements is cut off by turning the switch means 5 which comprisesthe transistor in FIG. 1 to off.

After that, at step (8), the terminal voltage (dv) of said secondarybattery being charged is measured, and at step (9), the results arestored into 1st memory means 15, that is, in memory I.

In the same manner, at step (10), the surface temperature (dt) of saidsecondary battery being charged is measured, and at step (13), theresults are stored into the same 1st memory means 15, that is, intomemory I.

Next, operation proceeds to step (12), at which the supply of chargingcurrent is starting once again to restart the charging operation, afterwhich at step (13) a judgment is made as to whether or not either thevoltage value or the temperature value just measured exceeds thepreestablished data limit value, and if said measured data does exceedsaid limit value, the judgment is made that an abnormal condition hasoccurred in the secondary battery being charged, and said chargingoperation is stopped.

If, however, both the voltage value and the temperature value justmeasured are judged normal at step (13), operation proceeds to step(14), at which the set value of counter III is decremented by 1, andoperation proceeds to step (15), at which a judgment is made as towhether or not the value of said counter III is zero, and if it is notzero, a wait is made until the value of counter III is zero, that is,until the corrected data reading time tc has elapsed, and after averification is made that the value of said counter III is zero,operation proceeds to step (16), at which the values of voltage data dvand temperature data dt obtained from the measurement just mad are addedto the respective values of voltage data dv and temperature data dtobtained at the immediately previous measurement, the results beingcumulatively stored separately into said 1st memory means 15.

Next, operation proceeds to step (17), at which 1 is subtracted from thesetting value L of counter II, and operation proceeds to step (18),where a judgment is made as to whether or not the setting value L ofsaid counter II is zero.

Thus, in the present invention, while voltage data and temperature dataare measured at least one time during said corrected data reading timetc, the associated operations are repeated during a preestablished time,that is during the measurement data amount of change reading samplingtime (ts), a preestablished number of times, that is, L, which causesrepetition of said measurements, said value of L being arbitrarilysettable.

Therefore, at step (18), if the setting value L of said counter II isnot zero, it means that the required number of measurements has not yetbeen reached, so that return is made to step (6), at which theabove-mentioned steps are repeated.

If, however, at step (18), the setting value L of said counter II iszero, this means that the required number of measurements has beenreached, so that operation proceeds to step (19), at which a calculationis performed to determine the sums, Dvn and Dtn, of the voltage andtemperature data values that had been stored into 1st memory means 15 Ltimes each corrected data reading time tc, these results being storedseparately into 2nd memory means 16 (memory II).

Next, at step (20), using the data that had been stored into said 2ndmemory means 16, the differences between the values Dv(n-1) and Dt(n-1)stored into memory II the immediately previous measurement and thevalues Dvn and Dtn of the current measurement, that is, the amounts ofchange between the data measured at the current measurement data amountof change reading sampling time (ts) and the data measured at theimmediately previous measurement data amount of change reading samplingtime (ts-1) are calculated, at the step (21) the resulting ΔDv and ΔTtare stored separately into said 3rd memory means 17 (memory III).

After this, at step (22), using the data ΔDv and ΔDt which had beenindividually cumulatively stored into 3rd memory means 17, said amountof change data ΔDv and ΔDt obtained at the current measurement dataamount of change reading time (ts1) are added respectively to theamounts of change data obtained at the immediately previous measurementdata amount of change reading time (ts0), the results of ΔTDv and ΔTDtbeing stored separately into 4th memory means 18 (memory IV).

At this step (22), said measurement data amount of change readingsampling time (ts) is set a number of times, for example M times, andthe accumulated sum of the amount of change data values obtained at eachof the sampling times (tsn) is calculated.

For this reason, at step (23), a judgment is made as to whether or notthe total number of data stored in said 4th memory means 18 (memory IV)is a preestablished number, for example M, and if the result of thisjudgment is NO, the judgment is made that the measurement data amount ofchange reading sampling time (ts) has not been repeated thepreestablished number of times M, and return is made to step (5), afterwhich step the above steps are repeated.

If, however, the result of step (23) is YES, operation proceeds to step(24), at which a calculation is made, with regard to the measuredvoltage data, from the overall amount of change data which had beenstored into said 4th memory means 18, to determine the difference valueΔHv (where ΔHv=ΔTDv(n-1)-ΔTDvn) between the amount of change from theimmediately previous measurement data, that is, the overall amount ofdata change ΔTDvn, which is based on the M data measurements at saidmeasurement data amount of change reading sampling times (ts1) to (tsm),and the amount of change from the current measurement data, that is, theoverall amount of change ΔTDv(n-1), which is based on the M datameasurements of said measurement data amount of change reading samplingtimes (ts0) to (tsM-1), and at which also a calculation is made, withregard to the measured temperature data, from the overall amount ofchange data which had been stored into said 4th memory means 18, todetermine the change ratio value ΔHt (where ΔHt=ΔTDt(n-1)/ΔTDtn) betweenthe amount of change from the immediately previous measurement data,that is the overall amount of data change ΔTDtn, which is based on the Mdata measurements at said measurement data amount of change readingsampling times (ts1) to (tsm) and the amount of change from the currentmeasurement data, that is the overall amount of data change ΔTDtn-1,which is based on the M data measurements of said measurement dataamount of change reading sampling times (ts0) to (tsM-1), the results,ΔHv and ΔHt, of said calculations being stored, respectively, in 6thmemory means 19(B) (memory VI) and 5th memory means 19(A) (memory V).

After that, at step (26), a judgment is made as to whether or notmeasurement data is voltage data, and if the result is NO, operationproceeds to step (27), at which, as shown in FIG. 6B, a judgment is madeas to whether or not said overall amount of change, ΔHt, of saidmeasurement data is larger than a preestablished value, for example thevalue K, and if the result is YES, operation proceeds to step (28).

Thus, the overall sum of said temperature data amounts of change ΔTDtnover the M times of measurement data amount of change reading samplingtime (ts1) to (tsM) is shift one said measurement data amount of changereading sampling time (ts) at a time, and if the change ratio withrespect to the overall sum said temperature data amounts of changeΔTDt(n+1) over the M times of measurement data amount of change readingsampling time (ts2) to (tsM+1) is large, indicating that the rate ofrise of said temperature measurement data has increased over a shortperiod of time, the judgment is made that said secondary battery beingcharged has reached the 100% charge level or the region of the 100%charge level, and the charging operation is stopped at this point.

The preestablished value K can be set as desired, and in the presentinvention, it is set as a value of, for example, 2 or greater.

That is, in the present invention, as shown in FIG. 2 through FIG. 4,for a secondary battery of any configuration, in the case in which thecharge level either reaches 100% or the region of 100%, or exceeds the100% level, since the measured temperature data rate of rise changessuddenly from its previous gradual increase to a rapid rate of rise,this condition is detected, enabling detection the reaching of the 100%level or the region of 100% charge level, or the exceeding of the 100%charge level.

If at step (27) the judgments result is NO, operation proceeds to step(29), at which, for the purpose of determining the overall amounttemperature measurement data amount of change, ΔTDt(n+2) for the Mtemperature data over the measurement data amount of change readingsampling time (ts3) to (tsM+2) by shifting said measurement data amountof change reading sampling time (ts) one at a time, after first deletingthe first of the M temperature measurement data currently stored inmemory V, return is made to step (23), after which the above operationsare repeated.

At step (28), if the result was YES, the operation proceeds to step(30), at which a judgment is made as to whether the change in saidoverall voltage data amount of change, that is ΔHv, is zero or negativeless than zero, and if the result was YES, operation proceeds to step(31), at which the setting value P of counter I is decremented by 1, andthen to step (32), at which a judgment is made as to whether the settingvalue P of said counter is P, and if the result is YES, operationproceeds to step (28), at which the charging operation is stopped. Whenthe result was NO at step (32), return is made to step (7), after whichthe above operations are repeated.

Thus, in the present invention, as shown in FIG. 2 through FIG. 4, for asecondary battery of any configuration, if the charge level reaches 100%or the region of 100% or exceeds 100%, the measured voltage data whichhad previously been rising is seen to start to fall or remain unchanged.

Therefore, in the present invention, for any secondary battery, todetect the condition in which the charge level has reached 100% or the100% region, a judgment is made as to whether the overall change in theamount of change, that is, the difference amount ΔHv is zero ornegative, and further a determination of whether the difference valueΔHv has been zero or negative for P times in a row, and if so, thejudgment is made that said secondary battery has reached the chargelevel of 100% or the region of charge level 100%, and the chargingoperation is then stopped.

In the present invention, the setting value P of said counter I can beestablished arbitrarily as desired, for example it can be set to a Pvalue of 3.

Therefore, in this case, although if said difference amount ΔHv is zeroor negative for 3 times in a row, the judgment is made that the chargelevel of said secondary battery has reached 100% or has reached the 100%region, and the charging operation will be stopped, if in any 3consecutive measurements the difference value ΔHv is positive even onetime, the setting value of said counter I is reset to the originalsetting value P and the above-stated judgment is repeated.

On the other hand, at step (30), if the result was NO, in step (33) thesetting value of counter I is reset to P, and operation returns to step(4), and thereafter each of the above-stated steps is repeated.

While in the above-described specific example of the present invention,said count I is set to an initial value of P, and counts downsequentially, in accordance with the result of measurements, so thatwhen the setting value P is 0 the judgment is made that the charge levelof the secondary battery is 100%, it is also possible to reverse this,by setting said counter I to an initial value of 0 and having saidcounter count up sequentially according to the results of measurements,and when the setting value of said counter I reached a preestablishedvalue of P, to make the judgment that the charge level of the secondarybattery is 100%.

However, in either of the above-described methods, during charging,there is a danger that the charging operation will be stopped if forsome reason the variation in the difference values of said data is zeroor negative three times consecutively, even at a point at which thecharge level is not that high, so that to solve this problem, in thepresent invention, since the output voltage of the various secondarybatteries in the region of 100% is known beforehand, it is desirable tomake the configuration such that the output voltage of said secondarybattery is constantly measured and the results monitored, so that theabove-described calculation method is only valid in the case in whichsaid output voltage is above 70% to 80% of the secondary battery'snominal output.

In the high-speed charging method for secondary batteries of the presentinvention, as described above, it is sufficient to at least measure theterminal voltage data of said secondary battery, so that the amount ofchange in the terminal voltage data are detected, and it is alsopossible to measure the surface temperature data of said secondarybattery, so that the change ratio in the surface temperature isdetected.

In addition, in the present invention, it is also possible to make useof both temperature data and voltage data to estimate the charge level.

In the present invention, for example, the basic data reading time tbrequired for reading data is set to 0.75 second, counter II value L isset to 4, the charge rate C at which said secondary battery is to becharged is set to 4, and constant A is set to 16.

In addition, at step (23) if the number of repetitions M is set to 8,said measurement data amount of change reading sampling time (ts) willbe 12 seconds, and the time required for 8 repetitions of themeasurement data amount of change reading sampling time (ts) will be 96seconds.

In the present invention, therefore, in the actual example given above,the measurement of either voltage or temperature will require aconsiderable amount time, and in such cases it is also possible, insteadof repeating the above-stated measurement data amount of change readingsampling time (ts) M times, to use individual values of the amount ofchange ΔDv and ΔDt to judge the charge level.

That is, in the charging method of the present invention, in the case inwhich said secondary battery has a considerable residual capacity, thereis a possibility that 100% charge level will be reached in a shortperiod of time, and since if the charging is continued without noticingthis, the temperature will rise, leading to a danger of deterioration ofthe secondary battery, to prevent this danger, it is desirable toprovide safety measures in addition to the basic charging method of thepresent invention.

Another specific example of the present invention will be described,with references made to the flowcharts of FIG. 10 and FIG. 11.

While the flowcharts of FIG. 10 and FIG. 11 are basically the same asthe flowcharts of FIG. 7 through FIG. 9 which show a high-speed chargingmethod for secondary batteries of the present invention, there areslight differences in the method of calculation and judging performed atindividual steps.

That is, in the specific example shown in FIG. 7 through FIG. 9, inperforming voltage measurements, for example, said voltage data istotaled within the measurement data amount of change reading samplingtime (ts), so that in the case of the charge level of said secondarybattery approaching 100%, because the voltage exhibits particularlysmall changes in a short period of time, it is desirable to constantlytrack the changes to detect such a condition, and in the presentinvention the configuration is made such that, for each measurement dataamount of change reading sampling time (ts), detection is performed ofhow said voltage data is varying, so that if said voltage data variationexhibits a particular condition, as shown in steps (24) through (32) insaid FIGS. 8 and 9 after repeating the voltage measurement data at least8 times at the measurement data amount of change reading sampling time(ts), the charging operation can be stopped before judging the chargingcondition.

FIG. 10 and FIG. 11 show the flowcharts of the operations performed inpracticing the other specific example of the present invention, whereinbecause step (7) through step (20) are the same as in the flowchart ofFIGS. 7 and 8, these steps are omitted from FIG. 10, with the flowchartbeginning with the step corresponding to step (20) of FIG. 8.

Note that in the following steps 120 and 121, the same calculation asindicated in step 20 in FIG. 8, are carried out.

Essentially, in FIG. 10 and FIG. 11, based on the data Dn that iscalculated and stored into the 2nd storage means before step (120), acalculation is performed to determine the difference ΔDv (whereΔDv=ΔDvn-ΔDv-1) between the voltage data Dvn-1 at the immediatelyprevious amount of change reading sampling time ts-1 and the voltagedata ΔDvn at the current amount of change reading sampling time ts, andin addition in step 121, a calculation is performed in the same mannerto determine the difference ΔDt (where ΔDt=ΔDtn-ΔDtn-1) between thetemperature data Dtn-1 at the previous amount of change reading samplingtime ts-1 and the temperature data Dtn at the current amount of changereading sampling time ts.

After the above is done, at step (122), said difference ΔDv (whereΔDv=ΔDvn-ΔDv-1), which is the amount of change in said voltage data, isstored into memory IV (V_(BUFF)), and at step (123), said difference(ΔDt=ΔDtn-ΔDtn-1), which is the amount of change in said temperaturedata is stored into memory IV (T_(BUFF)).

Next, in said specific example of the present invention, in particularwith regard to voltage data, it is desirable to detect the width ofvariation occurring over a short period of time, and for that reason, atstep (124), said difference ΔDv is judged as being either a non-zeropositive value or not, and if the result is YES, operation proceeds tostep (126) at which ΔS is reset to zero.

Essentially, what occurs is that, if the difference in the amount ofchange in said voltage data between the 1st measurement data amount ofchange reading sampling time (ts1) and the 2nd measurement data amountof change reading sampling time (ts2) is positive, this indicates thatsaid voltage measurement data is increasing, and in this case, thejudgment is made that the charge level of the secondary battery has notreached 100%, so that constant ΔS which indicates a change in saidvoltage measurement means is reset to zero and operation proceeds tostep (127).

On the other hand, a NO result occurs at step (124), that is, if thevoltage data is either decreasing or constant, operation proceedsinstead to step (125), at which the current said difference value ΔDv isadded to immediately previous value of constant ΔS and the valuepreestablished constant value X is subtracted from this, the resultbeing taken as the new value of constant ΔS.

In this example, since the value of ΔDv is negative, the result is thatboth the difference ΔDv and the preestablished constant Z are subtractedfrom the immediately previous value of constant ΔS.

In addition, the above-stated constant Z is a counting constant valuesuch that, when there is no change in the difference value ΔDv, it makesit appear as though there is change, and is set to, for example, Z=2.

Therefore, in this specific example, when the voltage data is at a peakvalue, and said peak value is being maintained, said constant ΔS isactually subtracted from.

Next, at step (127), a judgment is made as to whether said constant ΔSis equal to or less than a preestablished value of w, and if the resultis YES, since it is possible to assume that the charge level of thesecondary battery is at 100% or in the region of 100%, operationproceeds to step (135), at which the charging operation is stopped.

That is, in this specific example, said value w is set to, for example,6, and if said constant Z is 2 and said difference value ΔDv is zero 3times consecutively, that is, if there is no change, the followingsequence will occur.

After 1 ts: ΔS=ΔS-ΔDv-Z=0-0-2=-2

After 2 ts: ΔS=ΔS-ΔDv-Z=-2-0-2=-4

After 3 ts: ΔS=ΔS-ΔDv-Z=-4-0-2=-6

Thus, the charging operation will be stopped at the point at which thethird repetition of the measurement data amount of change readingsampling time (ts) is made.

By way of providing an explanation with more specific data if, forexample, the case in which the basic data reading time tb required forreading data is set as 0.75 second, the value L of counter II is set as4, the charging rate C at which the secondary battery is to be chargedis set to 4, and said constant A is set to 16.

In addition, in the case in which the number of repetitions M of themeasurement at the measurement data amount of change reading samplingtime (ts) is set to 8, and said constant w is set to -6, and theconstant Z is set to 2, if the erroneous recharging of a nickel-cadmiumbattery is done after the completion of charging is hypothesized, themeasurement data amount of change reading sampling time (ts) formeasuring the charging voltage characteristics would be (0.75×16/3)×4=16seconds, and the battery voltage, ΔDv, and ΔS with respect to eachmeasurement data amount of change reading sampling time (ts) would be asfollows.

    ______________________________________                                        ts      Battery voltage  ΔDv                                                                            ΔS                                      ______________________________________                                        1ts     632              632     0                                            2ts     631              -1     -3                                            3TS     629              -2     -7                                            ______________________________________                                    

From the above results, the charging operation with respect to thesecondary battery would be stopped at the measurement at the thirdmeasurement data amount of change reading sampling time (ts), the timerequired for this to occur being merely 48 milliseconds.

At step (128) in the flowchart of FIG. 10, from the amount of changedata for voltage-of each of the data stored in said memory IV (V_(BUFF))after the M repetitions of the operations of step (22) through step (23)of FIG. 8, a calculation performed to determine the difference value ΔHvbetween the current amount measurement data change, that is, the totalamount of change, ΔTDvn, based on the M measurement data at saidmeasurement value amount of change reading sampling time (ts1) to (tsM)and the total value of the immediately previous amount of measurementdata change, that is, the overall amount of change based on the Mmeasurement data at said measurement data amount of change readingsampling time (ts0) to (tsM-1), and at step (129) a judgment is made asto whether ΔHv is positive or negative or zero, and if it is positive,operation proceeds to step (131), at which the value N of an appropriatecounter is reset to zero, after which operation proceeds to step (132)

If, however, said difference value ΔHv is zero, the value of saidcounter is not changed, and if said difference value ΔHv is negative,operation proceeds to step (130), at which the value N of said counteris incremented by 1, after which operation proceeds to step (132).

The effect of this is that in this specific example, a judgment is madeof what condition, if any, said difference value ΔHv is maintainingcontinuously, and in the same manner as in the previously describedspecific example, in the case in which the value of said difference ΔHvis negative N times consecutively, said secondary battery is judged tohave reached a charge level of 100% or the region of 100% charge level,and said charging operation is stopped.

The value N of said counter can be set appropriately as desired, and inan actual example, can be set to, for example N=3.

In the present invention, because, as shown in step (124) through step(127), if ΔDv is zero, it is assumed that the negative condition exists,even at said step (129), even if said voltage measurement data ismaintaining a peak value, the condition in which the difference valueΔHv is zero will not occur, so that this will be counted as a negativevalue.

Then, operation proceeds to step (132), at which a judgment is made asto whether the value of N of said counter is 3, and if the result wasYES, the charging operation with respect to said secondary battery isstopped, but if the results was NO, operation proceeds step (133), atwhich, after said difference value ΔDt (ΔDt=Dtn-Dt(n-1)), which is thetemperature data amount of change stored into memory IV (T_(BUFF)) atstep (123) is used and M repetitions are made, a determination is madeof the current amount of measurement data change, that is, the overallamount of change, the total value ΔTDtn, based on the M measurement dataat the measurement data amount of change reading sampling time (ts1) to(tsM), and a determination is made of the immediately previous totalamount of change, which is the overall amount of change ΔTDt(n-1), whichis based on the M measurement data at said measurement value amount ofchange reading sampling time (ts0) to (tsM-1), and a judgment is made asto whether or not both these values are a preestablished value α.

In these operations, in performing the charging of said secondarybattery, because if some sort of error or misoperation causes a suddenrise in temperature in spite of the fact that the charge level has noteven reached the 100% region, an erroneous stoppage of said chargingoperation would occur, to avoid this condition, since the temperaturerise of said secondary battery during charging is known beforehand, datarelated to the normal amount of temperature change occurring when thecharge level reaches the 100% region is set as the required data, forexample by setting an appropriate value of α is set into an appropriatememory, in which case a return would be made to step (7) of FIG. 7,whereupon the above-described steps would be repeated.

In said step (133), in the case in which both the above-noted amounts oftotal temperature change are equal to or greater than the preestablishedvalue α, operation proceeds to step (134), at which a judgment is madeas to whether the rate of change ΔHt between the current amount ofmeasurement data change, that is, the overall amount of change ΔTDn,which is based on the M measurement data at said measurement data amountof change reading sampling time (ts1) to (tsM), and the immediatelyprevious amount of measurement data change, that is, the overall amountof change ΔTDtn-1, which is based on the M measurement data at saidmeasurement data amount of change reading sampling time (ts0) to(tsM-1), is or is not greater than a preestablished value, for exampleK, and if the result of this judgment is YES, the charging operation isstopped.

If, however, the result was NO, return is made to step (5) of FIG. 7,whereupon the above-described steps would be repeated.

What follows is an explanation of the results of using the secondarybattery charging method of the present invention to charge secondarybatteries of differing constituent elements and under different chargingconditions, with reference made to Table I through Table V and FIG. 12through FIG. 20.

Table I shows the case of using the secondary battery charging method ofthe present invention suitable for nickel-cadmium batteries having acharging rate of 0.25 C, and wherein the settings:

the basic data reading time required to read data, tb=0.75 second;

counter II value L=4;

charging rate C=0.25;

Setting constant A=16; and

Number of repetitions of the measurement operation to be performed ateach measurement data amount of change reading sampling time (ts) M=8were made for the execution of the charging operation.

In this specific example, the amount of change reading sampling time,ts, would be ts=(0.75×16/0.25)×4=192 seconds.

Table I shows the voltage measurement data at each measurement dataamount of change reading sampling time (ts), the total amount of voltagechange ΔTDv at step (122) of FIG. 10, and the counter value N at step(130) and step (131) of FIG. 10.

Essentially in Table I the battery voltage data is the raw data obtainedat each said measurement data amount of change reading sampling time(ts), and the overall total amount of change ΔTDv indicates thedifference value between the total of the shift values summed over 8times at each of the measurement data amount of change reading samplingtimes (ts1) to (ts8) and total of the shift values summed over 8 timesat each of the measurement data amount of change reading sampling times(ts2) to (ts9).

The count value N, in accordance with above-stated step (129) throughstep (131) in FIG. 10, is added to or subtracted from, depending uponwhether said difference value ΔHv is positive, negative, or zero.

That is, during the period from ts1 to ts8, since there is no previousdata, the output of said difference ΔHv is zero, so that the count valueN remains zero, but at ts9, said total amount of change ΔTDv becomes 32,so that the ΔHv value of -521 is negative, resulting in said count valueN being incremented by 1.

Next, at ts10, in the same manner, since said total amount of changeΔTDv becomes 24, said difference amount ΔHv takes the negative value of-8, so that said count value N is incremented by 1, making said countvalue 2.

In the same manner, because up to ts15 said difference value ΔHv iscontinuously negative, sound count value N is incremented by 1 eachtime, so that the count value is 7 at ts15.

However, in this specific example, in general, said count value is setto 3, so that the charging operation is stopped when said count valueexceeds 3, so that although in this specific example the chargingoperation is stopped at ts11, since the battery voltage of saidsecondary battery which has reached 100% charge level is knownbeforehand, it is possible to perform processing so that, as long asthat voltage is not exceeded, the data value of said counter is notvalid.

For this reason, in this specific example, if the battery voltage ofsaid secondary battery is set to, for example, to 580 V, and if theabove-stated count value N is made invalid when the battery voltageexceeds said 580 V, there will be no problem of the charging operationstopping at ts11.

Furthermore, at ts16, since the difference value ΔHv becomes -1, thecounter value is reset from 7 to 0.

The same type of operation is repeated, and at ts80 because the batteryvoltage is 600 V and said counter value is 3, said charging operation isstopped.

FIG. 12 shows a graph of the measurement data of Table I, with tsplotted along the horizontal axis, and in FIG. 13, plotted from the rawdata of FIG. 12, the solid line shows the plot of said total amount ofchange ΔTDv for each ts, and the dotted line shows said counter value Nplotted for each ts.

Table II shows the case of using the secondary battery charging methodof the present invention suitable for nickel-cadmium batteries having acharging rate of 3 C, and wherein the settings:

the basic data reading time required to read data, tb=0.75 second;

counter II value L=4;

charging rate C=3;

Setting constant A=16;

Number of repetitions of the measurement operation to be performed ateach measurement data amount of change reading sampling time (ts) M=8;and

constant K=2 were made for the execution of the charging operation.

In this specific example, the amount of change reading sampling time,ts, would be ts=(0.75×16/3)×4=16 seconds.

Table II shows the battery temperature measurement data at eachmeasurement data amount of change reading sampling time (ts), the totalamount of temperature change ΔTDt at step (123) of FIG. 10, and thechange ratio ΔHt of the amount of temperature change at step (134) ofFIG. 10.

Essentially in Table II the temperature data is the raw data obtained ateach said measurement data amount of change reading sampling time (ts),the overall total amount of temperature change ΔTDt indicates thedifference value between the total of the shift values summed over 8times at each of the measurement data amount of change reading samplingtimes (ts1) to (ts8) and total of the shift values summed over 8 timesat each of the measurement data amount of change reading sampling times(ts2) to (ts9), and ΔHt indicates the rate of change between adjacentvalues of ΔTDt, that is ΔHt=ΔTDtn/ΔTDtn-1.

In accordance with the operation of above-stated step (34) of FIG. 10,the change ratio of temperature change ΔHt is compared withabove-described preestablished constant value K=2, and if ΔHt is equalto or greater than 2 (i.e., ΔHt≧K), because it can be predicted that thecharge level has reached 100% or the 100% region, said chargingoperation is stopped.

In the data of Table II, if the denominator of the expression forΔHt=ΔTDtn/ΔTDtn-1 is zero, an error is indicated.

In this specific example, at ts57, the data for said rate of change oftemperature change ΔHt=ΔTDtn/ΔTDtn-1 exceeds the constant K=2, so thatat this point said charging operation is stopped.

FIG. 14 is a graph of with regard to battery temperature measurementdata shown in Table II, with ts plotted along the horizontal axis.

Table III shows the case of using the secondary battery charging methodof the present invention suitable for nickel-cadmium batteries having acharging rate of 3 C, and wherein the settings:

the basic data reading time required to read data, tb=0.75 second;

counter II value L=4;

charging rate C=3;

Setting constant A=16; and

the number of repetitions of the measurement operation to be performedat each measurement data amount of change reading sampling time (ts) M=8were made for the execution of the charging operation.

In this specific example, the amount of change reading sampling time,ts, would be ts=(0.75×16/3)×4=16 seconds.

Table III shows the battery voltage data at each measurement data amountof change reading sampling time (ts), the total amount of voltage changeΔTDv at step (122) of FIG. 10, and the counter value N at step (130) andstep (131) of FIG. 10.

Essentially, the battery voltage data and other data of Table III, arethe same type of data as in above Table I, and therefore no particularseparate explanation will be provided, although it can be said that thisindicates that the same type of operations as in the case of Table Ienable charging in a short period of time with a large current, and inparticular that, at 3 C, at the point of ts61, because charging iscompleted, the charge is seen to have been completed at atime-approximately 16 minutes from the start of charging operation.

FIG. 15 and FIG. 16 are graphs that correspond to above-discussed FIG.12 and FIG. 13.

Table IV shows the case of using the secondary battery charging methodof the present invention suitable for nickel-hydrogen batteries having acharging rate of 0.25 C, and wherein the settings:

the basic data reading time required to read data, tb=0.75 second;

counter II value L=4;

charging rate C=0.25;

Setting constant A=16; and

the number of repetitions of the measurement operation to be performedat each measurement data amount of change reading sampling time (ts) M=8were made for the execution of the charging operation.

In this specific example, the amount of change reading sampling time,ts, would be ts=(0.75×16/0.25)×4=192 seconds.

Table IV shows the battery voltage data at each measurement data amountof change reading sampling time (ts), the total amount of voltage changeΔTDv at step (122) of FIG. 10, and the counter value N at step (130) andstep (131) of FIG. 10.

Essentially, the battery voltage data and other data of Table IV, arethe same type of data as in above Table I, and therefore no particularseparate explanation will be provided, although it can be said that thisindicates that the same type of operations as in the case of Table Ienable complete charging of a new type of secondary battery, thenickel-hydrogen battery, at ts79, which is in a period of time of 252minutes.

FIG. 17 and FIG. 18 are the graphs that correspond to above-discussedFIG. 12 and FIG. 13.

Table V shows the case of using the secondary battery charging method ofthe present invention suitable for nickel-hydrogen batteries having acharging rate of 1 C, and wherein the settings:

the basic data reading time required to read data, tb=0.75 second;

counter II value L=4;

charging rate C=1;

Setting constant A=16; and

the number of repetitions of the measurement operation to be performedat each measurement data amount of change reading sampling time (ts) M=8were made for the execution of the charging operation.

In this specific example, the amount of change reading sampling time,ts, would be ts=(0.75×16/1)×4=48 seconds.

Table V shows the battery voltage data at each measurement data amountof change reading sampling time (ts), the total amount of voltage changeΔTDv at step (122) of FIG. 10, and the counter value N at step (130) andstep (131) of FIG. 10.

Essentially, the battery voltage data and other data of Table V, are thesame type of data as in above Table I, and therefore no particularseparate explanation will be provided, although it can be said that thisindicates that the same type of operations as in the case of Table Ienable complete charging of a new type of secondary battery, thenickel-hydrogen battery, at ts78, which is in a period of time of 62minutes, 24 seconds.

FIG. 19 and FIG. 20 are the graphs that correspond to above-discussedFIG. 12 and FIG. 13.

Because the high-speed charging method for secondary batteries of thepresent invention makes use of the above-described technicalconfiguration, even for secondary batteries of differing types, inconsideration of the mutually differing charging characteristicsexhibited by the secondary batteries, such as terminal voltage ortemperature, it is possible to determine the common characteristics ofsecondary batteries having differing constituent elements, to accuratedetermine point at which the charge level reaches nearly 100%, enablingnot only one and the same apparatus to be used to reliably chargesecondary batteries of differing construction, but also enabling theaccurate determination of the charge level during the charging process,the quick determination of the point at which the charge level reaches alevel of nearly 100%, and the stopping of the charging process at thatpoint, the result being not only a reliable avoidance of the problemencountered when the charging is continued even after the charge levelhas exceeded 100%, thereby causing the temperature of the secondarybattery to rise above its rated maximum temperature, leading to damageto said secondary battery, but also a determination of thecharacteristics of said secondary battery with respect to the speed ofcharge, or charge rate, thereby enabling charging of secondary batterieswhich are of the same constituent elements at different charge rates,further enabling in particular the precise high-speed charging ofsecondary batteries.

That is, in the present invention, in addition to being able to chargesecondary batteries having individually differing constructions, therebeing secondary batteries of the same type but having differing chargingrates, it is possible to also, in accordance with the charging rate thatis indicated as a specification, by executing sampling of the idealmeasurement values, to collect precise data, enabling accurate andhigh-speed charging.

                  TABLE I                                                         ______________________________________                                        tS     Battery Voltage (V)                                                                              ΔTDvn                                                                            N                                          ______________________________________                                         1     524                524      0                                           2     532                532      0                                           3     539                539      0                                           4     542                542      0                                           5     547                547      0                                           6     549                549      0                                           7     552                552      0                                           8     553                553      0                                           9     556                32       1                                          10     556                24       2                                          11     558                19       3                                          12     559                17       4                                          13     560                13       5                                          14     560                11       6                                          15     560                8        7                                          16     562                9        0                                          17     563                7        1                                          18     564                8        0                                          19     564                6        1                                          20     564                5        2                                          21     564                4        3                                          22     564                4        3                                          23     566                6        0                                          24     568                6        0                                          25     568                5        1                                          26     568                4        2                                          27     568                4        2                                          28     568                4        2                                          29     568                4        2                                          30     568                4        2                                          31     568                2        3                                          32     568                0        4                                          33     569                1        0                                          34     571                3        0                                          35     571                3        0                                          36     571                3        0                                          37     571                3        0                                          38     572                4        0                                          39     572                4        0                                          40     572                4        0                                          41     572                3        1                                          42     572                1        2                                          43     572                1        2                                          44     572                1        2                                          45     572                1        2                                          46     572                0        3                                          47     574                2        0                                          48     576                4        0                                          49     576                4        0                                          50     576                4        0                                          51     577                5        0                                          52     576                4        1                                          53     576                4        1                                          54     577                5        0                                          55     576                2        1                                          56     576                0        2                                          57     576                0        2                                          58     577                1        0                                          59     577                0        1                                          60     576                0        1                                          61     579                3        0                                          62     580                3        0                                          63     580                4        0                                          64     580                4        0                                          65     580                4        0                                          66     580                3        1                                          67     581                4        0                                          68     584                8        0                                          69     584                5        1                                          70     586                6        0                                          71     588                8        0                                          72     590                10       0                                          73     592                12       0                                          74     594                14       0                                          75     596                15       0                                          76     596                12       1                                          77     599                15       0                                          78     600                14       1                                          79     600                12       2                                          80     600                10       3                                          ______________________________________                                    

                  TABLE II                                                        ______________________________________                                                                       ΔTDtn/ΔTDtn-1                      tS   Battery Temperature (°C.)                                                               ΔTDtn                                                                            (K = 2)                                        ______________________________________                                         1   9.54             29.54    Error                                           2   9.32             29.32    0.99                                            3   8.65             28.65    0.98                                            4   8.65             28.65    1.00                                            5   8.65             28.65    1.00                                            6   8.65             28.65    1.00                                            7   8.65             28.65    1.00                                            8   8.65             28.65    1.00                                            9   7.99             -1.55    -0.05                                          10   7.76             -1.55    1.00                                           11   7.76             -0.89    0.57                                           12   7.76             -0.89    1.00                                           13   7.76             -0.89    1.00                                           14   7.76             -0.89    1.00                                           15   7.76             -0.89    1.00                                           16   7.76             -0.89    1.00                                           17   7.76             -0.22    0.25                                           18   7.76             0.00     0.00                                           19   7.76             0.00     Error                                          20   7.76             0.00     Error                                          21   7.76             0.00     Error                                          22   7.76             0.00     Error                                          23   7.76             0.00     Error                                          24   7.76             0.00     Error                                          25   7.10             -0.67    Error                                          26   6.88             -0.89    1.33                                           27   6.88             -0.89    1.00                                           28   6.88             -0.89    1.00                                           29   6.88             -0.89    1.00                                           30   6.88             -0.89    1.00                                           31   6.88             -0.89    1.00                                           32   6.88             -0.89    1.00                                           33   6.88             -0.22    0.25                                           34   6.88             0.00     0.00                                           35   6.88             0.00     Error                                          36   6.88             0.00     Error                                          37   6.88             0.00     Error                                          38   6.88             0.00     Error                                          39   6.88             0.00     Error                                          40   6.88             0.00     Error                                          41   6.88             0.00     Error                                          42   6.88             0.00     Error                                          43   6.88             0.00     Error                                          44   6.88             0.00     Error                                          45   6.88             0.00     Error                                          46   6.88             0.00     Error                                          47   6.88             0.00     Error                                          48   6.88             0.00     Error                                          49   6.88             0.00     Error                                          50   6.88             0.00     Error                                          51   6.88             0.00     Error                                          52   6.88             0.00     Error                                          53   6.88             0.00     Error                                          54   6.88             0.00     Error                                          55   6.88             0.00     Error                                          56   7.10             0.22     Error                                          57   7.54             0.67     3.00≧K                                  58   7.76             0.89     1.33                                           59   7.99             1.11     1.25                                           60   8.21             1.33     1.20                                           61   8.43             1.55     1.17                                           62   8.87             2.00     1.29                                           63   1.09             4.22     2.11                                           ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        tS     Battery Voltage (V)                                                                              ΔTDvn                                                                            N                                          ______________________________________                                         1     529                529      0                                           2     542                542      0                                           3     547                547      0                                           4     550                550      0                                           5     552                552      0                                           6     556                556      0                                           7     556                556      0                                           8     560                560      0                                           9     560                31       1                                          10     562                20       2                                          11     564                17       3                                          12     564                14       4                                          13     566                14       4                                          14     568                12       5                                          15     568                12       5                                          16     568                8        6                                          17     572                12       0                                          18     572                10       1                                          19     572                8        2                                          20     572                8        2                                          21     575                9        0                                          22     576                8        1                                          23     576                8        1                                          24     576                8        1                                          25     576                4        2                                          26     579                7        0                                          27     580                8        0                                          28     580                8        0                                          29     580                5        1                                          30     580                4        2                                          31     582                6        0                                          32     584                8        0                                          33     584                8        0                                          34     584                5        1                                          35     584                4        2                                          36     586                6        0                                          37     588                8        0                                          38     588                8        0                                          39     588                6        1                                          40     588                4        2                                          41     592                8        0                                          42     592                8        0                                          43     592                8        0                                          44     594                8        0                                          45     596                8        0                                          46     597                9        0                                          47     600                12       0                                          48     601                13       0                                          49     604                12       1                                          50     606                14       0                                          51     609                17       0                                          52     612                18       0                                          53     616                20       0                                          54     620                23       0                                          55     624                24       0                                          56     627                26       0                                          57     630                26       0                                          58     632                26       0                                          59     632                23       1                                          60     632                20       2                                          61     632                16       3                                          ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        tS     Battery Voltage (V)                                                                              ΔTDvn                                                                            N                                          ______________________________________                                         1     513                513      0                                           2     525                525      0                                           3     534                534      0                                           4     541                541      0                                           5     545                545      0                                           6     549                549      0                                           7     552                552      0                                           8     554                554      0                                           9     556                43       1                                          10     556                31       2                                          11     558                24       3                                          12     560                19       4                                          13     560                15       5                                          14     560                11       6                                          15     560                8        7                                          16     564                10       0                                          17     564                8        1                                          18     564                8        1                                          19     564                6        2                                          20     564                4        3                                          21     564                4        3                                          22     565                5        0                                          23     568                8        0                                          24     568                4        1                                          25     568                4        1                                          26     568                4        1                                          27     568                4        1                                          28     568                4        1                                          29     568                4        1                                          30     568                3        2                                          31     568                0        3                                          32     568                0        3                                          33     568                0        3                                          34     568                0        3                                          35     569                1        0                                          36     570                2        0                                          37     570                2        0                                          38     570                2        1                                          39     571                3        0                                          40     571                3        0                                          41     571                3        0                                          42     571                3        0                                          43     572                3        1                                          44     572                2        2                                          45     572                2        3                                          46     572                2        0                                          47     572                1        1                                          48     572                1        1                                          49     572                1        1                                          50     572                1        1                                          51     574                2        0                                          52     576                4        1                                          53     576                4        1                                          54     576                4        1                                          55     576                4        1                                          56     576                4        1                                          57     576                4        1                                          58     576                4        1                                          59     576                2        2                                          60     578                2        2                                          61     580                4        0                                          62     580                4        0                                          63     580                4        0                                          64     580                4        0                                          65     580                4        0                                          66     583                7        0                                          67     584                8        0                                          68     584                6        1                                          69     587                7        2                                          70     588                8        0                                          71     591                11       0                                          72     592                12       0                                          73     595                15       0                                          74     596                13       1                                          75     597                13       1                                          76     600                16       0                                          77     600                13       1                                          78     600                12       2                                          79     600                9        3                                          ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        tS     Battery Voltage (V)                                                                              ΔTDvn                                                                            N                                          ______________________________________                                         1     543                543      0                                           2     560                560      0                                           3     564                564      0                                           4     565                565      0                                           5     568                568      0                                           6     568                568      0                                           7     568                568      0                                           8     568                568      0                                           9     568                25       1                                          10     572                12       2                                          11     572                8        3                                          12     572                7        4                                          13     572                4        5                                          14     572                4        5                                          15     572                4        5                                          16     572                4        5                                          17     572                4        5                                          18     573                1        6                                          19     575                3        0                                          20     576                4        0                                          21     576                4        0                                          22     576                4        0                                          23     576                4        0                                          24     576                4        0                                          25     576                4        0                                          26     576                3        1                                          27     576                1        2                                          28     576                0        3                                          29     576                0        3                                          30     576                0        3                                          31     576                0        3                                          32     576                0        3                                          33     576                0        3                                          34     576                0        3                                          35     578                2        0                                          36     579                3        0                                          37     580                4        0                                          38     580                4        0                                          39     580                4        0                                          40     580                4        0                                          41     580                4        0                                          42     580                4        0                                          43     580                2        1                                          44     580                1        2                                          45     580                0        3                                          46     580                0        3                                          47     580                0        3                                          48     580                0        3                                          49     583                3        0                                          50     584                4        0                                          51     584                4        0                                          52     584                4        0                                          53     584                4        0                                          54     584                4        0                                          55     584                4        0                                          56     584                4        0                                          57     586                3        1                                          58     588                4        0                                          59     588                4        0                                          60     588                4        0                                          61     588                4        0                                          62     589                5        0                                          63     592                8        0                                          64     592                8        0                                          65     592                6        1                                          66     595                7        0                                          67     596                8        0                                          68     598                10       0                                          69     600                12       0                                          70     602                13       0                                          71     604                12       1                                          72     606                14       0                                          73     608                16       0                                          74     609                14       1                                          75     612                16       0                                          76     612                14       1                                          77     612                12       2                                          78     612                10       3                                          ______________________________________                                    

What is claimed is:
 1. A method of charging a secondary battery,comprising:a step 1 which sets the basic data reading time tb requiredto read data; a step 2 which sets the charging rate C; a step 3 whichsets the adjusted data reading time tc, according to the set chargingrate C and said basic data reading time tb, said corrected data readingtime tc being unique to said charging rate C; a step 4 which, during thecharging operation, uses an appropriate sampling means to measure theterminal voltage of said secondary battery at least one time during eachsaid adjusted data reading time tc, and which stores the measuredvoltage data at that time into an appropriate 1st memory means; a step 5which repeats the operation of said step 4 a predetermined number oftimes L, takes the summation of the plurality of voltage data obtainedin each adjusted data reading time tc, and stores the resulting amountof adjusted voltage value Dvn over the amount of voltage data changereading sampling time ts (where ts=L×tc) into an appropriate 2nd memorymeans; a step 6 which calculates the difference between the amount ofadjusted voltage value Dv1 for the 1st sampling time (ts1) and theamount of adjusted voltage value Dv2 for the next, 2nd, sampling time(ts2) obtained in step 5, and which stores the resulting difference inamount of change ΔDv in a 3rd memory means; a step 7 which continuouslyrepeats said step 6 a predetermined number of times M, and which takesthe summation of each of the difference values of ΔDv1 to ΔDvM (Mvalues) obtained at each amount of change reading sampling time (ts),and determines the amount of voltage data change ΔTDv for the overallsaid amount of change reading sampling time t (where t=ts×M), theresults being stored in a 4th memory means; a step 8 which performs acalculation, based on the amount of voltage data change ΔTDv stored insaid 4th memory means, to determine the difference ΔHv between thevoltage amount of change ΔTDv1 measured from over the first overallamount of change reading sampling time (t1) established as running fromsaid 1st sampling time (ts1) to the mth sampling time (tsM) for thepredetermined M-th sampling, and the voltage amount of change ΔTDv2measured from over the second overall amount of change reading samplingtime established as running from said 2nd sampling time (ts2) to the(m+1)th sampling time (tsM+1) for the predetermined M+1-th sampling,said calculated difference ΔHv (where ΔHv=ΔTDv2-ΔTDv1) being stored in a5th memory means; a step 9 which repeats said step 8 while calculatingthe difference value ΔHvn (where ΔHvn=ΔTDv(n+1)-ΔTDvn) between theamount of voltage changes ΔTDvn and ΔTDv(n+1) at each pair of adjacentoverall amount of change sampling times tn and tn+1, and stores thecalculated results in 5th memory means; a step 10 which judges whethereach of the m amounts of differences in amount of voltage changes ΔHv1to ΔHvm are positive (zero or greater than zero) or negative (less thanzero); and a step 11 which judges, in the sequence of occurrence of saiddifferences in amount of voltage changes ΔHv1 to ΔHvm, whether or notsaid difference in amount of voltage change ΔHv is zero or negative forS times continuously, and if said difference in amount of voltage changeΔHv is zero or negative S times continuously, stops said charging.
 2. Amethod of charging a secondary battery, comprising:a step 1 which setsthe basic data reading time tb required to read data; a step 2 whichsets the charging rate C; a step 3 which sets the adjusted data readingtime tc, according to the set charging rate C and said basic datareading time tb, said adjusted data reading time tc being unique to saidcharging rate C; a step 4 which, during the charging operation, uses anappropriate sampling means to measure the temperature of said secondarybattery at least one time during each said adjusted data reading timetc, and which stores the measured temperature data at that time in anappropriate 1st memory means; a step 5 which repeats the operation ofsaid step 4 a predetermined number of times L, takes the summation ofthe plurality of data obtained in each adjusted data reading time tc,and stores the resulting amount of adjusted temperature value Dtn overthe amount of temperature data change reading sampling time ts (wherets=L×tc) into an appropriate 2nd memory means; a step 6 which calculatesthe difference between the amount of adjusted temperature value Dt1 forthe 1st sampling time (ts1) and the amount of adjusted temperature valueDt2 for the next, 2nd, sampling time (ts2) obtained in step 5, and whichstores the resulting difference in amount of change ΔDt in a 3rd memorymeans; a step 7 which continuously repeats said step 6 a predeterminednumber of times M, and which takes the summation of each of thedifference values of ΔDt1 to ΔDtM (M values) obtained at each amount ofchange reading sampling time (ts), and determines the amount oftemperature data change ΔTDt for the overall said amount of temperaturechange reading sampling time t (where t=ts×M), the results being storedin a 4th memory means; a step 8 which performs a calculation, based onthe values of amount of temperature data change ΔTDt stores in said 4thmemory means, to determine the ratio between the temperature amount ofchange ΔTDt1 measured from over a first overall amount of change readingsampling time t1 established as running from said 1st sampling time(ts1) to the sampling time (tsM) for the predetermined M-th sampling,and the temperature amount of change ΔTDt2 measured from over a secondoverall amount of change reading sampling time t2 established as runningfrom said 2nd sampling time (ts2) to the sampling time (tsM+1) for thepredetermined M+1-th sampling, said calculated ratio ΔHt (whereΔHt=ΔTDt2/ΔTDt1) being stored in a 5th memory means; a step 9 whichrepeats the operations of said step 8 while calculating the ratio valueΔHtn (where ΔHtn=ΔTDt(n+1)/ΔTDtn) between the amount of temperaturechanges ΔTDtn and ΔTDt(n+1) at each paid of adjacent overall amount ofchange sampling times tn and tn+1, and stores the calculated results in5th memory means; a step 10 which judges from the information stored insaid 5th memory means whether the ratio ΔHm between two adjacent saidtemperature amounts of change is equal to or greater than or is lessthan a given value K; and a step 11 which, if the temperature amount ofchange ratio ΔHm value is equal to or greater than the given value K,stops said charging.
 3. A method of charging a secondary battery,comprising:a step 1 which sets the basic data reading time tb requiredto read data; a step 2 which sets the charging rate C; a step 3 whichsets the adjusted data reading time tc, according to the set chargingrate C and said basic data reading time tb, said adjusted data readingtime tc being unique to said charging rate C; a step 4 which, during thecharging operation, uses an appropriate sampling means to measure thetemperature and the terminal voltage of said secondary battery,respectively, at least one time during each said adjusted data readingtime tc, and which stores the temperature data and the terminal voltagedata at that time into an appropriate 1st memory means, respectively; astep 5 which repeats the operation of said step 4 a predetermined numberof times L, takes the individual summation of the plurality of batterytemperature data and voltage data obtained at each adjusted data readingtime tc, and stores the resulting respective amounts of adjustedtemperature value Dtn and adjusted voltage value Dvn over thetemperature data and terminal voltage data reading sampling time ts(where ts=L×tc) into an appropriate 2nd memory means; a step 6 whichcalculates the difference between the amounts of adjusted voltage valueDv1 and adjusted temperature value Dt1 for the 1st sampling time (ts1)and the respective amounts of adjusted voltage value Dv2 and adjustedtemperature value Dt2 for the next, 2nd, sampling time (ts2) obtained instep 5, and which stores the resulting difference amounts ΔD fortemperature data and terminal voltage data (ΔDv and ΔDt) in a 3rd memorymeans; a step 7 which continuously repeats step 6 a predetermined numberof times M, and which takes the summation of each of the values of ΔDv1to ΔDvM (M values) and ΔDt1 to ΔDtM (M values) obtained at each amountof change reading sampling time (ts), and determines the amount oftemperature data change and the amount of terminal voltage data change,ΔTDt and ΔTDv, for the overall said amount of change reading samplingtime t (where t=ts×M), the results being stored in a 4th memory means; astep 8 which performs a calculation, based on the values of amount ofvoltage data change ΔTDv stored in said 4th memory means, to determinethe difference between the amount of voltage change ΔTDt1 measured fromover a first overall amount of voltage change reading sampling time t1established as running from said 1st sampling time (ts1) to the samplingtime (tsM) for the predetermined M-th sampling, and the amount ofvoltage change ΔTDt2 measured from over a second overall amount ofvoltage change reading sampling time t2 established as running from said2nd sampling time (ts2) to the sampling time (tsM+1) for thepredetermined M+1-th sampling, said calculated difference ΔHv (whereΔHv=ΔTDv2-ΔTDv1) being stored in a 6th memory means; a step 9 whichrepeats step 8 while calculating the difference value ΔHvn (whereΔHvn=ΔTDv(n+1)-ΔTDvn) between the amount of voltage changes ΔTDvn andΔTDv(n+1) at each pair of adjacent overall amount of change samplingtimes tn and tn+1, and stores the calculated results in 6th memorymeans; a step 10 which judges whether the m amounts of voltage changesΔHv1 to ΔHvm are positive (zero or greater than zero) or negative (lessthan zero); a step 11 which performs a calculation, based on the valuesof amount of temperature data change ΔTDt stored in said 4th memorymeans, to determine the ratio ΔHt between the amount of temperaturechange ΔTDt1 measured from over a first overall amount of temperaturechange reading sampling time t1 established as running from said 1stsampling time (ts1) to the sampling time (tsM) for the predeterminedM-th sampling, and the amount of temperature change ΔTDt2 measured fromover a second overall amount of temperature change reading sampling timet2 established as running from said 2nd sampling time (ts2) to thesampling time (tsM+1) for the predetermined M+1-th sampling, saidcalculated difference ΔHt (where ΔHt=ΔTDt2/ΔTDt1) being stored in a 5thmemory means; a step 12 which repeats the operations of step 11 whilecalculating the change ratio value ΔHtn (where ΔHtn=ΔTDt(n+1)/ΔTDtn)between the amount of temperature changes ΔTDtn and ΔTDt(n+1) at eachpair of adjacent overall amount of temperature change sampling times tnand tn+1 respectively, and stores the calculated results in 5th memorymeans; a step 13 which judges from the information stored in said 5thmemory means whether the ratio ΔHtm between two adjacent said amounts oftemperature change is equal to or greater than or is less than a givenvalue K; and a step 14 which judges, for said temperature change ratiosΔHtm equal to or greater than the predetermined value of K and in thesequence of occurrence of said differences in amount of voltage changesΔHv1 to ΔHvm, whether or not said difference in amount of voltage changeΔHv is zero or negative for S times continuously, and if said differencein amount of voltage change is zero or negative S times continuously,stops said charging.
 4. A method of charging a secondary batteryaccording to claim 1, 2, or 3, wherein when said sampling means is usedduring charging to measure the terminal voltage or to measure thetemperature of said secondary battery at each corrected data readingtime tc, the supply of charging current to said secondary battery iscutoff when making the measurement.
 5. A method of charging a secondarybattery according to claim 1, 2, or 3, wherein when said sampling meansis used during charging to measure the terminal voltage or to measurethe temperature of said secondary battery at each corrected data readingtime tc, if measurement of even one of these values indicates a levelexceeding a predetermined abnormal value level, said charging operationis interrupted.
 6. A method of charging a secondary battery according toclaim 1, 2, or 3, wherein said corrected data reading time tc iscalculated from said charging rate C and said basic data reading time tbby the expression tc=tb×A/C, in which A is a constant.
 7. A method ofcharging a secondary battery according to claim 1, 2, or 3, wherein in astep which repeats measurement of voltage data M times continuously eachsaid data change reading sampling time ts, at each time said voltagedata is measured each said data change reading sampling time ts, theamount of change ΔTDv in voltage data is calculated, a judgment is madeas to whether said amount of voltage data change ΔTDv is positive,negative, or zero, and if it is positive, an appropriate counter valueΔS which judges a condition of a change in amount of the voltage datachange ΔTDv, is reset to zero, but if said amount of voltage data changeΔTDv is negative or zero, said counter value ΔS has added to it saidΔTDv value, said counter value ΔS being updated to the added value,after which said counter value ΔS is compared with a preestablishedreference value W, and if said counter value ΔS is smaller than saidreference value W, said charging operation is stopped.
 8. A method forcharging a secondary battery according to claim 7, wherein when thevalue of said voltage data amount of change ΔTDv is zero, apreestablished value Z is subtracted from said counter value ΔS.
 9. Anapparatus for charging a secondary battery comprising:acurrent-supplying means for supplying electrical current to the cells ofa secondary battery requiring charging; a switch means provided betweensaid current-supplying means and said secondary battery being charged; atemperature measurement means for measuring the temperature of saidcells; a sampling means for operating said temperature-measurement meansto measure the temperature of said cells with the desired samplinginterval; a charging-control means which is connected to said samplingmeans and controls said switch means; a charging rate setting meanswhich sets the charging rate C; a corrected data reading time settingmeans which, based on the charging rate C set at said charging ratesetting means, calculates from a preestablished basic data reading timetb the corrected data reading time tc, the value of which ischaracteristic to said charging rate C; an amount of data change readingsampling time setting means which multiplies the corrected data readingtime tc by a preestablished value L to set the temperature data amountof change reading sampling time ts; an overall sampling time settingmeans which multiplies said data amount of change reading sampling timets by a preestablished value M to set the overall sampling time t; a 1stmemory means which stores the values of temperature data dtn measured ateach said corrected data reading time tc; a 2nd memory means whichstores the data Dtn which is the summation of a predetermined member Lvalues of temperature data dtn stored in said 1st memory means; a 3rdmemory means which, from the data Dtn stored in said 2nd memory means,stores the difference between data Dt(n-1) measured at the previousamount of change reading sampling time ts and data Dtn measured at thecurrent amount of change reading sampling time ts+1, this differencevalue being ΔDt (where ΔDt=Dtn-Dt(n-1)); a 4th memory means which storesthe amount of temperature data change ΔTDt obtained by taking thesummation of each of the M amounts of temperature data obtained at eachamount of change reading sampling time (ts) in the overall amount ofchange reading sampling time t (where t=ts×M) obtained by repeating saidamount of change reading sampling time (ts) M the required number of Mtimes; a 5th memory means which, with regard to the temperature dataamount of change ΔTDt stored in said 4th memory means, stores the changeratio ΔHt calculated between the amount of temperature data change ΔTDtnat the 1st overall amount of change reading sampling time tn and theamount of temperature data change ΔTDt(n+1) at the 2nd overall amount ofchange reading sampling time tn+1, which is formed by shifting the timeby one amount of change reading sampling time (ts), said change ratiobeing ΔHt (where ΔHt=ΔTDt(n+1)/ΔTDtn); a 1st judgment means whichcompares said temperature change ratio ΔHtm between said amounts oftemperature change with a preestablished reference value K, and if saidchange ratio ΔHtm between said amounts of temperature change exceedssaid reference value K, outputs a signal which stops said charging; aprocessing means which processes each of the individual data stored byeach of said means; and a central processing means which controls theoperation of each said means.
 10. An apparatus for charging a secondarybattery comprising:a current-supplying means for supplying electricalcurrent to the cells of a secondary battery requiring charging; a switchmeans provided between said current-supplying means and said secondarybattery being charged; a terminal voltage measurement means formeasuring the terminal voltage of said cells; a sampling means foroperating said terminal voltage measurement means to measure theterminal voltage of said cells with the desired sampling interval; acharging-control means which is connected to said sampling means andcontrols said switch means; a charging rate setting means which sets thecharging rate C; a corrected data reading time setting means which,based on the charging rate C set at said charging rate setting means,calculates from a preestablished basic data reading time tb thecorrected data reading time tc, the value of which is characteristic tosaid charging rate C; an amount of data change reading sampling timesetting means which multiplies the corrected data reading time tc by apreestablished value L to set the temperature data amount of changereading sampling time ts; a overall sampling time setting means whichmultiplies said data amount of change reading sampling time ts by apreestablished value M to set the overall sampling time t; a 1st memorymeans which stores the values of terminal voltage data dvn measured eachsaid corrected data reading time tc; a 2nd memory means which stores thedata Dvn which is the summation of the L values of temperature data dvnstored in said 1st memory means; a 3rd memory means which, from the dataDvn stored in said 2nd memory means, stores the difference between dataDv(n-1) measured at the previous amount of change reading sampling timets and data Dvn measured at the current amount of change readingsampling time ts+1, this difference value being ΔDv (whereΔDv=Dvn-Dv(n-1)); a 4th memory means which stores the amount of terminalvoltage data change ΔTDv obtained by taking the summation each of the Mamounts of voltage change data obtained at each amount of change readingsampling time in the overall amount of change reading sampling time t(where t=ts×M) obtained by repeating said amount of change readingsampling time (ts) M the required number of M times; a 6th memory meanswhich, with regard to the terminal voltage data amount of change ΔTDvstored in said 4th memory means, stores the difference ΔHvm calculatedbetween the amount of voltage data change ΔTDvn measured in the 1stoverall amount of data change reading sampling time tn and the amount ofvoltage data change ΔTDv(n+1) measured in the 2nd overall amount of datachange reading sampling time tn+1, which is formed by shifting the timeby one amount of change reading sampling time (ts), said differencebeing ΔHvm (where ΔHvm=ΔHvm=Hv(m+1)-Hvm); a judgment means which, withregard to each the m values of voltage data amounts of changedifferences ΔHv1 to ΔHvm serially stored in said 6th memory means, makesa judgment as to whether each one of said differences ΔHv1 to ΔHvm ispositive (zero or larger) or negative (less than zero), and whichperforms said judgment processing in the sequence of occurrence of saidvoltage data amount of change differences ΔHv1 to ΔHvm, and if each oneof the successively measured voltage data amount of change differenceΔHv show a negative value, at least a preestablished number of times S,continuously, stops said charging operation; a processing means whichprocesses each of the individual data stored by each of said means; anda central processing means which controls the operation of each saidmeans.
 11. A method of charging a secondary battery according to claim4, wherein when said sampling means is used during charging to measurethe terminal voltage or to measure the temperature of said secondarybattery at each corrected data reading time tc, if measurement of evenone of these values indicates a level exceeding a predetermined abnormalvalue level, said charging operation is interrupted.
 12. A method ofcharging a secondary battery according to claim 4, wherein saidcorrected data reading time tc is calculated from said charging rate Cand said basic data reading time tb by the expression tc=tb×A/C, inwhich A is a constant.
 13. A method of charging a secondary batteryaccording to claim 5, wherein said corrected data reading time tc iscalculated from said charging rate C and said basic data reading time tbby the expression tc=tb×A/C, in which A is a constant.
 14. A method ofcharging a secondary battery according to claim 4, wherein in a stepwhich repeats measurement of voltage data M times continuously each saiddata change reading sampling time ts, at each time said voltage data ismeasured each said data change reading sampling time ts, the amount ofchange ΔTDv in voltage data is calculated, a judgment is made as towhether said amount of voltage data change ΔTDv is positive, negative,or zero, and if it is positive, an appropriate counter value ΔS whichjudges a condition of a change in amount of the voltage data changeΔTDv, is reset to zero, but if said amount of voltage data change ΔTDvis negative or zero, said counter value ΔS has added to it said ΔTDvvalue, said counter value ΔS being updated to the added value, afterwhich said counter value ΔS is compared with a preestablished referencevalue W, and if said counter value ΔS is smaller than said referencevalue W, said charging operation is stopped.
 15. A method of charging asecondary battery according to claim 5, wherein in a step which repeatsmeasurement of voltage data M times continuously each said data changereading sampling time ts, at each time said voltage data is measuredeach said data change reading sampling time ts, the amount of changeΔTDv in voltage data is calculated, a judgment is made as to whethersaid amount of voltage data change ΔTDv is positive, negative, or zero,and if it is positive, an appropriate counter value ΔS which judges acondition of a change in amount of the voltage data change ΔTDv, isreset to zero, but if said amount of voltage data change ΔTDv isnegative or zero, said counter value ΔS has added to it said ΔTDv value,said counter value ΔS being updated to the added value, after which saidcounter value ΔS is compared with a preestablished reference value W,and if said counter value ΔS is smaller than said reference value W,said charging operation is stopped.
 16. A method of charging a secondarybattery according to claim 6, wherein in a step which repeatsmeasurement of voltage data M times continuously each said data changereading sampling time ts, at each time said voltage data is measuredeach said data change reading sampling time ts, the amount of changeΔTDv in voltage data is calculated, a judgment is made as to whethersaid amount of voltage data change ΔTDv is positive, negative, or zero,and if it is positive, an appropriate counter value ΔS which judges acondition of a change in amount of the voltage data change ΔTDv, isreset to zero, but if said amount of voltage data change ΔTDv isnegative or zero, said counter value ΔS has added to it said ΔTDv value,said counter value ΔS being updated to the added value, after which saidcounter value ΔS is compared with a preestablished reference value W,and if said counter value ΔS is smaller than said reference value W,said charging operation is stopped.
 17. A method for charging asecondary battery according to claim 14, wherein when the value of saidvoltage data amount of change ΔTDv is zero, a preestablished value Z issubtracted from said counter value ΔS.
 18. A method for charging asecondary battery according to claim 15, wherein when the value of saidvoltage data amount of change ΔTDv is zero, a preestablished value Z issubtracted from said counter value ΔS.
 19. A method for charging asecondary battery according to claim 16, wherein when the value of saidvoltage data amount of change ΔTDv is zero, a preestablished value Z issubtracted from said counter value ΔS.